Washington (CNN) -- For political junkies, 2013 was expected to be a quiet year following the presidential election and it basically followed the script. 

Nonetheless, there were some interesting developments at the ballot box. 

New Jersey, as expected, returned Gov. Chris Christie to office and also sent Cory Booker to the U.S. Senate. Bill de Blasio became the first Democrat elected New York City Mayor in two decades, and Democrats, led by Terry McAuliffe, swept the top three executive offices in Virginia for the first time in recent memory. 

Were these outcomes isolated or do they mean anything for 2014, when candidates will heat up the campaign trail big time ahead of next November's congressional midterms and key gubernatorial elections? 

In the new year, 435 House seats are up as are 35 in the Senate. There will be 36 gubernatorial races as well. Most of these campaigns won't be nail biters, but there could be collective power shifts in Washington and in state houses. 

Here, CNN Politics focuses on the Senate, where Republicans aim to retake control. Republicans must pick up six seats to claim the majority and key races are wide open at this point. 

The top 12 campaign questions of 2014 

Five key races: 

Kentucky 

The incumbent is Senate Minority Leader Mitch McConnell, who is under pressure from two fronts: Democrats, naturally, and from a tea party challenger within his own Republican Party who says he's not conservative enough. 

While McConnell is likely to defeat his primary opponent, Matt Bevin, he is expending money and other resources he'd rather use in a general election campaign against Kentucky Secretary of State Alison Lundergan Grimes. 
What happened in New Jersey?
Gov. Chris Christie to office