When the Senate Isn't Enough

"Eh, I'm not running for president," Reid said, "so I have a very different constituency than Brownback does."

People who have served in the Senate say members are often uneasy with outward expressions of ambition -- particularly the ambitions of their colleagues. It's human nature for a senator to ask, "Who does that guy think he is?" says former senator Gary Hart, who ran for president in 1984 and 1988. He says he detected resentment and jealousy from other senators, especially during the heady days of his 1984 campaign after he stunned frontrunner Walter Mondale in the New Hampshire primary.

"They were angry at themselves for not running while I did," Hart says.

Candidates also use their Senate platform to play against perceptions of themselves. Clinton (D-N.Y.) has been accused of this repeatedly. She has co-sponsored legislation with conservative colleagues such as Brownback and Santorum and, recently, a bill that would outlaw flag burning. And many suspected that Bayh (D-Ind.) was trying to defy his moderate image -- or at least win points among liberals -- when he voted against the nomination of a popular Supreme Court nominee from his home state (John Roberts) and against the nomination of Condoleezza Rice for secretary of state.

Or, who knows, maybe these senators were acting on principle.

Either way: "No matter what, people in the Senate will reflexively say, 'Oh, he's voting that way because he's running for president,' " says former senator Bob Kerrey, who ran in 1992.

"That's unless they happen to be voting with you," he adds, "in which case they are a profile in courage."

Mark Leibovich is a reporter for The Post's Style section.