Historically,electoral realignments occur

A) when new issues combine with economic or political crises to mobilize new voters
And persuade large numbers of voters to reexamine their traditional partisan loyalties.
B) when Congress approves of them.
C) after midterm congressional elections but not after presidential elections.
D) only when the Constitution is amended.

Electoral realignments happen when a new issue arises, and they combine with economic or political crises that mobilize new voters and convinces them to reexamine their traditional partisan loyalties. This has been a common pattern in American political history, such as the realignment that occurred in the 1930s during the Great Depression, where Franklin Roosevelt's New Deal policies helped to realign the Democratic Party as a champion of working-class and minority interests while older Republican constituencies, such as wealthy Northeasterners, began moving to the GOP.