How Congress works in regard to how many years Congress people serve in Senate and House

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 Members of the House of Representatives serve two-year terms and are considered for reelection every even year. Senators however, serve six-year terms and elections to the Senate are staggered over even years so that only about 1/3 of the Senate is up for reelection during any election.

How Congress Works | Congressman Tim Walberg - House.gov