Marriages of convenience rarely work out.

So when Senate Minority Leader Mitch McConnell, R-Ky., picked Jesse Benton, political consigliere to the Paul family — Rand and Ron — to manage his 2014 re-election race, campaign sharps began placing bets on how long it would last.

The union hit a rough patch last week when it was revealed that Benton told a former Ron Paul aide that he was “holding my nose for two years” because of the benefits his current position probably would have for Rand Paul’s future (presidential) prospects.

Of course, all political people knew that Benton — and by extension, the Paul family — were using McConnell the same way McConnell was using them. The Senate minority leader got credibility among tea party conservatives thinking of trying to oust him in a primary. Benton et al got more establishment credibility for Rand Paul’s all-but-certain 2016 bid.

But the fact that Benton said it out loud — albeit to a guy who was surreptitiously taping the conversation — is bad news for McConnell’s campaign.

The senator is facing a primary threat from his ideological right in the form of self-funder Matt Bevin.

Benton’s comments amount to a ready-made TV ad for Bevin to show how McConnell is trying to pull the wool over conservatives’ eyes.

McConnell — and Benton — sought to poke fun at the whole thing, tweeting a picture of Benton holding his nose standing next to McConnell. Caption: “Nothing smells worse than Obamacare!” Well played, but not enough.

Mitch McConnell, for holding your nose to spite your face, you had the worst week in Washington. Congrats, or something.

Chris Cillizza is a political reporter for The Washington Post and anchors the Fix blog.