On the other hand, federal midterm elections (where only Congress and not the president is up for election) are usually regarded as a referendum on the sitting president's performance, with voters either voting in or out the president's party's candidates, which in turn helps the next session of Congress to either pass or block the president's agenda, respectively. The two-party system in the U.S. As noted above, the modern political party system in the United States is a two-party system, with the parties being the Democratic Party and the Republican Party. Explanations for why America has a two party system include: The traditional American electoral format of single-member districts where the candidate with the most votes wins ("first-past-the-post" system), which according to Duverger's law favors the two-party system. This is in contrast to multi-seat electoral districts and proportional representation found in some other democracies. the 19th century innovation of printing "party tickets" to pass out to prospective voters to cast in ballot boxes (originally, voters went to the polls and publicly stated which candidate they supported), "consolidated the power of the major parties". Printed party "tickets" (ballots) were eventually replaced by uniform ballots provided by the state, when states began to adopt the Australian Secret Ballot Method. This gave state legislatures—dominated by Democrats and Republicans—the opportunity to handicap new rising parties with ballot access laws requiring a large number of petition signatures from citizens and giving the petitioners a short length of time to gather the signatures. Some (Nelson W. Polsby writing before 1997) have argued that the lack of central control of the parties in America means they have become as much "labels" to mobilize voters as political organizations, and that "variations (sometimes subtle, sometimes blatant) in the 50 political cultures of the states yield considerable differences", suggesting that "the American two-party system" actually masks "something more like a hundred-party system." Others (Lee Drutman, Daniel J. Hopkins writing before 2018) argue that in the 21st century, along with becoming overly partisan, America politics has become overly focused on national issues and "nationalized". Major parties Democratic Party The Democratic Party is one of two major political parties in the U.S. Founded as the Democratic Party in 1828 by Andrew Jackson and Martin Van Buren, it is the oldest extant voter-based political party in the world. Until the mid-20th century, the Democratic Party was the dominant party among white southerners, and