Ambition caused Republicans to miss votes this Congress, while Democratic leadership was most likely to be missing the "independents" in their caucus.
Why it matters: Thin margins make vote attendance even more critical for congressional leaders — as seen last week when Republicans were in uproar over their colleagues missing judicial votes.
Zoom in: Sens. Tim Scott (R-S.C.), JD Vance (R-Ohio) and Mike Braun (R-Ind.) all were on the campaign trail heavily this Congress — as a presidential candidate, VP candidate and gubernatorial candidate, respectively.
Sen. Bill Hagerty (R-Tenn.) is also a frequent traveler with President-elect Trump and was a top Cabinet contender.
Sen. John Barrasso (R-Wyo.), who is set to be Senate majority whip, missed weeks of votes this year due to his wife's illness and death.
Sens. Joe Manchin (I-W.Va.) and Kyrsten Sinema (I-Ariz.) proved to be dissenting voices in the Democratic Party before going independent, and are now retiring.
Sen. Bernie Sanders (I-Vt.) is also often at odds with Democratic leadership.
Sen. John Fetterman (D-Pa.) has battled mental illness, causing him to miss votes.