Votes largely fell on party lines
"The first article alleging Clinton lied under oath when he testified before Independent Counsel Ken Starr's grand jury about the details of his extramarital affair with Lewinsky was adopted on a 228-206, largely party-line vote. Only five Democrats voted for that article, and five Republicans against.
"Article II failed 229-205, with many more Republican defections.
"But the GOP majority again prevailed, 221-212, on Article III accusing Clinton of obstructing justice by tampering with witnesses and taking other steps to conceal his affair with Lewinsky."
The Senate convicts with a two thirds vote. The dems would impeach if they had the chance, regardless of the unlikely chance of conviction in the Senate. This is not a loyal opposition. They will do anything for political gain.
It's not a question of loyalty. Attempted impeachment convictions that fail are not likely to work out well for the party bringing the impeachment, politically speaking. It'll make them look shrill and petty in time of war.
A straight party-line vote, which is what this would be, would not make the Dems look good. They need to get a few liberal Republicans onboard (like McCain and Specter) so that they can market themselves as "bipartisan". Without that, nobody but the most diehard Democrats will buy into their game.