Four states chose their nominees for key midterm election races Tuesday: Pennsylvania, Nebraska, Idaho, and Oregon.

The stakes were by far the highest for national Democrats in Pennsylvania, where some of their best House pickup opportunities in the country will be on the ballot this fall, along with a US Senate seat and a governorship they’ll have to defend.

Idaho and Oregon also had competitive Republican primaries for governor, while Nebraska has one key US House seat Democrats are targeting and one of the few Republican-held US Senate seats that will be on the ballot this fall. Here’s what to watch.

Pennsylvania Senate Republican primary: Lou Barletta versus Jim Christiana

Update: Lou Barletta is projected to win the Republican primary.

Who is the Democrat? Incumbent Sen. Bob Casey, first elected in the 2006 election. His dad was the governor a few decades ago.

Who are the Republicans? US Rep. Lou Barletta and state Rep. Jim Christiana.

What’s the story? Barletta is the establishment’s favored son in this race, but Christiana is running on a “Washington outsider” message. We just saw in the Indiana Senate primary last week that House Republicans like Barletta are having a hard time winning over voters at the polls right now. But whoever wins will have a tough time against Casey. The most recent polls put him up by at least 16 points over Barletta. The Cook Political Report says this race is a Likely Democratic win. But it can’t be ignored after Donald Trump’s surprising win here in 2016.

Pennsylvania governor Republican primary: who will challenge Gov. Tom Wolf?

Update: Scott Wagner is projected to win the Republican primary.

Who is the Democrat? Incumbent Gov. Tom Wolf, first elected in 2014.

Who are the Republicans? It’s a three-way race in Tuesday’s GOP primary: state Sen. Scott Wagner versus attorney Laura Ellsworth versus former paratrooper Paul Mango. Wagner has the endorsements of both Steve Bannon and Maryland Gov. Larry Hogan, which is quite the spectrum. Conservative stalwart Sen. Tom Cotton endorsed Mango; former presidential candidate Carly Fiorina backed Ellsworth.

What’s the story? Wolf seems to be in good shape. Morning Consult places his approval rating at 45 percent, with 39 percent disapproval. Cook says the race leans toward Wolf. A March poll showed him with solid leads over all his potential Republican challengers. Still, the GOP has hopes of picking up this seat in a state Trump surprisingly won in 2016.

Pennsylvania’s First Congressional District primaries: Republican Rep. Brian Fitzpatrick runs again

Update: Rep. Brian Fitzpatrick is projected to win the Republican primary.

Who are the Democrats? The local party is backing Scott Wallace, a wealthy lawyer who’s already put $2.5 million of his own money into the race. He’s being challenged by Rachel Reddick, a former Navy prosecutor blasting him as a “Maryland multimillionaire.” Reddick has her own problem, though — she was a registered Republican until last year. Progressive activist Steve Bacher is also running.

Who are the Republicans? Rep. Brian Fitzpatrick is the incumbent and expected nominee, though he’s facing a primary challenge from the right, from attorney Dean Malik.

What’s the story? Hillary Clinton won this eastern district by 2 percentage points, so it’s a top target for Democrats this fall. Yet Fitzpatrick, a former FBI agent who’s only in his first term in Congress, could be a tough target. Some Democrats hope Wallace will win so he can self-fund and they can spend their general election money elsewhere.

Pennsylvania’s Fifth Congressional District: a very crowded primary for a near-certain Democratic pickup

Update: Mary Scanlon is the projected winner in the Democratic primary.

Who are the Democrats? Ten Democrats are running in this incredibly crowded race, so we won’t list them all. Lawyer Mary Gay Scanlon and former prosecutor Ashley Lunkenheimer raised the most money, but a recent poll showed state Rep. Greg Vitali (who’s foresworn big-dollar fundraising) in the hunt too.

Who is the Republican? Pearl Kim, a former prosecutor, is unopposed for the GOP nomination.

What’s the story? This open seat in the southeast of the state was vacated by Republican Rep. Pat Meehan, who resigned due to accusations that he sexually harassed an aide. But it’s already a near-certain Democratic pickup — Pennsylvania’s new map changed this from a swing district to one Hillary Clinton won by 28 points. So the main drama is which of the 10 Democratic candidates in the race will emerge triumphant in an incredibly crowded primary race — and no one really knows! With no obvious frontrunner, it’s entirely possible someone could win with less than 20 percent of the vote.

Pennsylvania’s Seventh Congressional District: a three-way ideological showdown among Democrats

Update: Susan Wild is the projected winner in the Democratic primary.

Who are the Democrats? There’s a clear ideological contrast among the leading Democratic candidates in this race. John Morganelli, the Northampton County district attorney, is well-known in the district — but he’s also anti-abortion and pro-gun, and has said harsh things about unauthorized immigration and positive things about Donald Trump. Greg Edwards is an African-American pastor supported by progressive activist groups, including the Bernie Sanders-aligned Our Revolution. Susan Wild, former Allentown city solicitor, is backed by Democratic women’s groups like Emily’s List and NARAL.

Who are the Republicans? Former Olympic cyclist Marty Nothstein is facing off against businessman Dean Browning.

What’s the story? There’s a wide-open race to succeed former Republican Rep. Charlie Dent, who had been in Congress for 14 years and co-chaired the House GOP’s moderate “Tuesday Group” but retired due to frustration with polarized politics. And under the new map, Clinton won the district by 1 point, making it a prime pickup opportunity. But if Morganelli wins, Democrats fear he’d be an unreliable vote for the party in Congress.

Pennsylvania’s Eighth Congressional District: a Democrat in a Trumpy district

Update: John Chrin is the projected winner in the Republican primary.

Who is the Democrat? Rep. Matt Cartwright, first elected to Congress in 2012, represents one of the most conservative US House districts currently held by a Democrat.

Who are the Republicans? Wealthy self-funder John Chrin hopes to win the GOP nomination, even though he doesn’t actually live in the district anymore under the new map. Former prison guard Robert Kuniegel and former police officer Joe Peters are also running.

What’s the story? In a normal year, Cartwright would be a top target for the GOP — Trump won his district by nearly 10 points. But with the midterm environment looking tough for Republicans in general, the Cook Political Report currently ranks this race as Likely Democratic.

Pennsylvania’s 10th Congressional District: a reach contest for Democrats

Who are the Democrats? The top fundraisers on the Democratic side are public health scientist Eric Ding and former Capitol Hill and Obama administration staffer Shavonnia Corbin-Johnson. Air Force veteran Alan Howe and pastor George Scott are also in the race.

Who is the Republican? Rep. Scott Perry, an Iraq War veteran who was first elected in 2012.

What’s the story? Perry represents a district Trump won by about 9 points — so it’s not out of the question that Democrats could pick it up in a wave year. It’s definitely not one of their easiest pickup opportunities in Pennsylvania, though, and the party lacks a top-tier recruit.

Pennsylvania’s 11th Congressional District: twin ideological challenges for a GOP incumbent

Update: Rep. Lloyd Smucker is projected to win the Republican primary.

Who is the Democrat? Jess King, a progressive nonprofit leader backed by Bernie Sanders, is running unopposed.

Who are the Republicans? Rep. Lloyd Smucker is facing a primary challenge from the right, from Chet Beiler. Beiler has pledged to join the Freedom Caucus if elected.

What’s the story? Smucker seemed to be one of the few incumbent Republicans to benefit from Pennsylvania’s new map, since his district became more conservative. Still, if he can best Beiler’s right-wing ideological challenge in the primary, he’ll have to rebut King’s progressive platform in the general.

Pennsylvania’s 12th Congressional District: the incumbent tries to defend his record on opioids

Update: Rep. Tom Marino is projected to win the Republican primary.

Who are the Democrats? Drug and alcohol counselor Judy Herschel and Penn State professor Marc Friedenberg are competing for the nomination.

Who is the Republican? Rep. Tom Marino is running for reelection, but he’s facing a primary challenge from Bradford County Commissioner Doug McLinko.

What’s the story? Marino was nominated as Trump’s drug czar last year, but he withdrew from consideration after reports described his role in passing a law that critics say hindered the government’s response to the opioid epidemic. So McLinko is trying to make Marino’s record the centerpiece of his primary challenge. Trump won by 36 points, so it’s probably safely in the GOP’s hands for the general.

Pennsylvania’s 14th Congressional District: Rick Saccone is back

Update: Guy Reschenthaler is the projected winner in the Republican primary. Bibiana Boerio is the projected winner in the Democratic primary.

Who are the Democrats? Four Democrats are vying for their party’s nomination, with emergency physician Bob Solomon putting more than $100,000 of his own money into the race against former Ford executive Bibiana Boerio, veteran Tom Prigg, and Adam Sedlock.

Who is the Republican? State Rep. Rick Saccone, who lost against Conor Lamb in March’s special election and was generally viewed as a weak candidate, is running in the Republican primary. Some prominent Republicans hope state Sen. Guy Reschenthaler will win the primary instead of Saccone.

What’s the story? Conor Lamb won a seat in Congress in that special election, but that was under Pennsylvania’s old map, in a district that was then split between the new 17th (where he’s running) and the more conservative new 14th. Trump won this new district by 29 points, so it will likely be, technically, a Republican pickup canceling out a Democratic gain elsewhere.

Pennsylvania’s 16th Congressional District Democratic primary: who will take on Rep. Mike Kelly?

Update: Ron DiNicola is the projected winner in the Democratic primary.

Who are the Democrats? Attorney Ron DiNicola is the leading fundraiser. Physician Robert Multari and Chris Rieger are also running.

Who is the Republican? Rep. Mike Kelly.

What’s the story? This northwestern district went to Trump by 20 points, but to Mitt Romney in 2012 by only 5 points — so the Cook Political Report deems it Likely Republican rather than safe. It’s probably a reach for Democrats, though.

Nebraska

Nebraska Senate: who will take on Sen. Deb Fischer?

Update: Jane Raybould is the projected winner in the Democratic primary.

Who are the Democrats? The name to watch here is Jane Raybould, Lincoln City Council member and former candidate for lieutenant governor. She’s raising by far the most money, though there are several other Democrats on the ballot on Tuesday.

Who are the Republicans? Incumbent Sen. Deb Fischer was first elected in 2012. She is a “mainstream Republican” through and through.

What’s the story? Fischer will almost certainly win. Her campaign found her leading Raybould by 17 points a few months back. But if 2018 starts to get really weird, we’ll have to check back in with the Cornhuskers. Cook did rate Nebraska as merely Likely R, and if you’re looking for a wild card, Nebraska is one of those states that could be hurt by the president’s escalating trade war. Raybould is promising to be “an independent voice” while slamming the incumbent as a “Washington Republican.”

Nebraska Second Congressional District: Republican Don Bacon looks vulnerable

Who are the Democrats? Former Rep. Brad Ashford is looking to reclaim the congressional seat he won in 2014 and lost in 2016. The moderate ex-Republican has the official DCCC Red to Blue imprimatur. But he does have a real primary race: Kara Eastman, president of a local nonprofit, is also running. She has a more progressive platform, backing Medicare-for-all.

Who are the Republicans? Incumbent Rep. Don Bacon. He beat Ashford in 2016 by a single percentage point.

What’s the story? This district, Omaha and the surrounding area, is much swingier than the rest of Nebraska. Barack Obama won it in 2008. Ashford got elected in 2014. Trump won here by just 2 percentage points in 2016. Cook and the other major election prognosticators think this is a toss-up race in 2018. Ashford would come with obvious advantages if he wins the Democratic primary (he won here before, after all), but Democrats are likely to contest this race no matter what. It could be a key pickup in their bid to flip 24 seats and take back the House.

Idaho

Idaho governor: a huge opportunity for a rising Republican

Who are the Republicans? Three GOP candidates are making a big enough splash to win this thing. There’s the establishment guy: Brad Little, the current lieutenant governor, who has held that position since 2009. There’s the right-wing conservative: four-term House member Rep. Raul Labrador, one of the founding members of the Freedom Caucus. Third is a political outsider: Tommy Ahlquist, a former physician and wealthy commercial real estate developer from Boise who has been signaling to culture war messaging but is closer to Little on his business-centric politics. Whoever wins this primary will likely be the next governor of Idaho.

Who are the Democrats? Paulette Jordan, a 38-year-old two-term Idaho state legislator and a member of the Coeur d’Alene Tribe, represents the young, fresh progressive face in the race. She’s picked up all the national endorsements, from Planned Parenthood to People for Bernie Sanders. But the state’s Democratic establishment is lining up behind A.J. Balukoff, a 72-year-old businessman who ran for governor in 2014.

What’s the story? The next Idaho governor will have the chance to be a rising star leading a rapidly growing state. With an unemployment rate below the national average and low cost of living, Idaho experienced a 2.2 percent population growth in one year. And a fast-growing tech sector means that influx of new residents is expected to continue. A majority of residents think Idaho is heading in the right direction with Republican leadership. But the next governor will have to address the growing pains that come with that.

The growing population and business market are paired with a poor education system that’s poised to create some major workforce problems in the state down the line. This race will likely also have huge implications for the state’s health care system, as Idaho is one of several states that could also have an initiative to expand Medicaid on the ballot this November. The state’s next governor could be tasked with implementing a Medicaid expansion.

Oregon

Oregon governor: a crowded Republican primary to take on Kate Brown

Who’s the Democrat? After Oregon’s Gov. John Kitzhaber resigned amid a corruption and influence-peddling scandal involving his fiancée, Kate Brown succeeded to the job and won a 2016 special election to serve the rest of his term.

Who are the Republicans? State Rep. Knute Buehler has been viewed as the frontrunner for some time, but the Oregon Statesman Journal recently wrote that the primary looks tighter than expected, with retired Navy Capt. Greg Wooldridge and businessman Sam Carpenter among the other candidates in the hunt and attacking Buehler as being too moderate.

What’s the story? Brown’s approval rating isn’t great, the state continues to face budget problems, and Republicans hope that after 32 straight years of Democratic governors, Oregon is ready for a change. But that could well be a heavy lift when Trump is so unpopular in the blue state.