With the party conventions almost upon us, I confess I still can’t figure out Mitt Romney. Throughout the primary season, he dispatched his rivals with remorseless efficiency. Probably my favorite moment came in the November debate in which Gov. Rick Perry couldn’t remember the name of one of the cabinet agencies he wanted to eliminate. Ever so cruelly, Romney suggested, “The EPA?”

Perry dug his own grave — and Mitt gleefully shoveled dirt on top of him.

It made perfect sense at the time: You don’t succeed in Mitt Romney’s line of business without the capability of being a remorseless bastard when you need to be.

Yet, time and again, Romney behaves like a goody-two-shoes teacher’s pet.

This business with Sen. Harry Reid and his “Mitt may have paid no taxes” gambit is a perfect example.

When Romney decided not to release any more than a year-and-change of returns, he and his staff must have anticipated there would be low-level chatter for weeks, months — possibly for the duration of the campaign. Team Romney calculated that it could endure such chatter, coming as it no doubt would from easily ignored muckrakers, bloggers, and partisan activists. What Team Romney did not anticipate — what virtually no one anticipated — is that such idle chatter would emanate from the U.S. Senate Majority Leader.

Yet instead of publicly calling Reid a disgraceful, rumormongering cowardly pitbull who is beneath contempt, Romney falls back on unwritten rules of decorum:

“I don’t really believe that he’s got any kind of a credible source,” Romney said. “I don’t know who gave him this line of reasoning, whether it came from the White House or the DNC or a staffer, but he ought to say where it came from, and then we can find out whether that person has any credibility. I know they don’t.”

He said Reid also has “lost a lot of credibility.”

Translation: “Hey, no fair!”

Again, I say, I can’t figure this dude out.