Most congressional contests use plurality voting: the candidate with more votes than any opponent wins. Because each seat is awarded separately, a party's national congressional vote is not pooled and converted proportionally into seats. A party receiving 20 percent in each of five districts can win no seat if it never finishes first. House boundaries can also change after reapportionment and redistricting, while Senate constituencies remain whole states. A national Senate vote total does not translate proportionally into seats because states receive equal representation and only one class is normally exposed in a cycle.

A presidential general election is national in attention but state based in legal operation. The nominees campaign for one national office and present a joint ticket with their vice-presidential running mates. Voters participate through elections administered under state law, and their ballots choose slates of presidential electors. The Constitution supplies the term and electoral framework; states administer registration, ballot access, voting, counting, and certification within federal limits.

The presidential process unfolds through distinct stages. Voters cast ballots in November; states canvass and certify results; electors meet in their states; certificates are transmitted; and Congress counts the electoral votes. A network projection has no legal power to appoint electors. Presidential and congressional candidates may share a ballot and party label, but their contests remain separate. A strong presidential nominee may help lower-ballot allies by attracting supporters, yet no presidential vote transfers automatically to a House or Senate candidate. Begin every comparison with the office, constituency, term, and vote-conversion rule. Those facts explain why the same political mood can replace the House quickly, affect only the scheduled Senate class, and choose a president through a separate state-based process.

Video lesson: Election Basics: Crash Course Government and Politics #36