The Republicans absorbed many Northern Whigs, as well as some anti-slavery Democrats and much of the Free Soil Party.
Many Southern Whigs became Democrats, though some formed the Constitutional Union Party to contest the 1860 presidential election.
[2] A period of realignment commenced following the onset of the Great Depression, as President Franklin D. Roosevelt constructed the successful New Deal coalition.
Over the ensuing decades, Roosevelt's Democrats embraced several tenets of modern American liberalism, while the Republican Party tended to favor conservatism.
The civil rights movement had also deepened existing racial tensions in much of the Southern United States, and Republican politicians developed strategies that successfully contributed to the political realignment of many white, conservative voters in the South who had traditionally supported the Democratic Party rather than the Republican Party.
There have also been several instances of politicians continuing to be a member of a political party while running other campaigns as an independent.
Moreover, former U.S. Secretary of Agriculture and Democrat Mike Espy endorsed incumbent Republican Governor of Mississippi Haley Barbour for reelection in 2007.
On August 3, 2017, West Virginia Governor Jim Justice announced that he had rejoined the Republican Party after having been elected as a Democrat less than a year prior.
He made the announcement at a rally in Huntington alongside Trump and claimed that he was returning to the GOP because he could not help the president while he was a Democrat.
In 2019, Democratic congressman Jeff Van Drew left the party because of his opposition to Trump's first impeachment and his own political beliefs.
Conversely, Republican congressman Justin Amash of Michigan left the GOP to become an independent on July 4, 2019 due to his opposition to Trump.
Arlen Specter, a former US Senator of Pennsylvania, cited his uncertainty of winning a Republican primary as one reason for his move to the Democratic Party.