"Is it helpful that you have a majority leader throwing a fundraiser for your opponent? Probably not," adds Holmes. "But McConnell's a grown up and he's certainly not going to use that as a reason to not get a result."
When Reid faced a bruising re-election four years ago, McConnell never campaigned with the GOP challenger, Sharron Angle.
But the National Republican Senatorial Committee, which is the campaign arm of the Senate GOP, did go up with some tough commercials attacking Reid.
The Senate tradition that the chamber's top two leaders would refrain from actively campaigning against each other back home ended in 2004, when then-Senate Republican leader Bill Frist got involved in the successful drive to defeat then-Senate Democratic Leader Tom Daschle of South Dakota.
Despite all this bad blood over the past few years, Manley points out that both "Reid and McConnell "are smart enough to know when to compromise."