Rick Santorum is claiming Mitt Romney and Ron Paul forged some secret backroom non-aggression pact with each other, and today a Think Progress study is adding fuel to that story. Out of the 20 debates Paul has participated in so far, he’s directly attacked the other candidates 39 times – but hasn’t once laid his gloves on Romney:

Rick Santorum has directly accused Paul and Romney of working together, noting “their commercials look a lot alike, and so do their attacks.” A review by ThinkProgress of the 20 GOP debates suggests Santorum might be onto something.

While Paul has freely attacked Romney’s top rivals, he has never once attacked Romney.

Twenty debates and no Romney attacks? As Allahpundit quips, “Out: Conspiracy theories advanced by Ron Paul. In: Conspiracy theories involving Ron Paul.”

There’s clearly a pattern here, but it’s important to get perspective. The same “Romney alliance” rumor has gone around about other candidates, including Michele Bachmann before she dropped out. Legal Insurrection detailed the theory last December:

The speculation was fueled by Bachmann’s relentless and often inaccurate attacks on everyone who rose to be the lead challenger to Romney, first Pawlenty, then Perry, then Cain, and most recently Newt.  Yet Romney was spared the wrath of Bachmann, other than the “Newt Romney” line.

Bachmann’s former campaign manager Ed Rollins later speculated that she took it easy on Romney because she was holding out for a VP slot. A less calculated reason could be that she knew she wasn’t going to win and didn’t want to alienate the party’s most likely nominee.

But Paul also has a personal and professional interest in maintaining good relations with Romney. Like Bachmann, he knows he can’t win the nomination. But he’d like some signs of respect at the GOP convention, and wants to leave as many bridges intact in the party as he can for his son. Beyond that, Paul and Romney seem to have a friendly rapport, while Paul has had a rocky personal history with both Newt Gingrich and Rick Santorum. It’s a perfectly logical reason, but not a scandalous one.