It’s hardly a secret what Mitt Romney is up to in trying to invoke Bill Clinton’s name in ads and speeches. Clinton was the good Democrat. The sensible centrist. And—let’s lower our voices here—the white one. It’s been transparent since it started in May, made all the more so this week by using Clinton to slam Obama on welfare. Clinton responded to that, and that was fine as far as it went. But I really hope he does more—a lot more. Clinton has tremendous power in this election, and I hope he uses the occasion of his convention speech, and for that matter the whole fall campaign, to destroy Romney, saying to every swing voter: “If you voted for me, you’d be nuts to vote for this guy. He’s making up a version of me to serve his own purposes, and he’s against almost everything I stood for and stand for.”

Romney’s welfare attack on the administration is appallingly dishonest. Glenn Kessler, The Washington Post’s fact checker, gave the Romney ad four Pinocchios, his most extreme rating. (He also gave the Obama camp’s response, about Romney as governor signing a 2005 letter seeking waivers, three Pinocchios.) The new waivers on work requirements don’t come anywhere near gutting the law or ending work requirements. The ad doesn’t take liberties with the truth. It is just a total lie.

Clinton called Romney on it, but he’s going to have to do more. It’s obvious that using Clinton to try to appeal to the Clinton swing voter is pretty central to the Romney plan. As soon as Romney polished off Rick Santorum back in May, he started singing Clinton’s praises. It was his way to appeal to the center. He doesn’t have the courage to do that by taking any actual centrist positions, of course. The positions remain hard right. So he chose to do it instead by using Clinton as the vehicle through which to make ominous insinuations about Obama, implying to audiences that Clinton was the sober pragmatist whose legacy the ultra-liberal Obama had defenestrated.

It was dishonest enough in May: There was not and is not a single major Obama initiative that Clinton has gone on the record opposing. But now the insinuation is racial: Clinton made those lazy blacks work, and Obama wants to go back to giving them “free stuff.”

It will be interesting to see how this plays out. When Clinton signed the welfare bill, he expressed the hope and belief that the politics of race-baiting had come to an end. We’ll find out in the next few weeks whether he was right. Indefensible as Romney’s ad is, I think the administration made a mistake by even treading into these waters in an election year. There are political people in the executive agencies, and of course in the White House itself, who are supposed to run these traps and imagine just these scenarios. I disagree with liberals who’ve written that there was nothing the administration could have done about this, because how could they anticipate that Romney would just lie? You have to assume that Republicans will just lie. You can’t bring the government to a grinding halt because of that assumption, but there are certain hot buttons that are better pushed after Nov. 6, and this was one of them.

Clinton’s statement was good, but in all likelihood Romney is going to keep pumping this, and I hope Clinton pushes back hard on this and other fronts. He is, by a few light years, Obama’s most valuable surrogate in this election. If I’m a swing voter in Ohio, and Barack Obama or Harry Reid or even Sherrod Brown (God love the guy) tries to assure me that Obama has my back, I’ll tune it out. But if Bill Clinton tells me that, by cracky I’ll listen.

But Clinton can do more than validate Obama. He has the authority to shred Romney. Some conservatives appear to have this fantasy, expressed by Jennifer Rubin in The Washington Post yesterday, that Clinton has more in common with Romney. That’s too ridiculous even to bother rebutting, except to note that it can provide fodder for some great laugh lines built around the idea that yes, back when he was president, Clinton did agree with Romney on several things, like abortion rights and the assault weapons ban. Then Romney changed all his positions.And, of course, there is the one issue that looms above all others, which Clinton could frame as a simple and devastating question: “Governor, if you think I’m so great, if you agree with me so much, why don’t you support my tax rate for the top 1 percent?” Boom.

Wednesday night of the Democratic convention, Clinton will place Obama’s name in nomination. I’ve seen him tear a convention hall to pieces. That Los Angeles speech in 2000 may have been his best ever, especially with that Roman gladiator-style intro, the camera following him up a lengthy hallway from the green room to the podium as the fanfare blared and crowd went bonkers. If anything, he is today even more beloved by Democrats, because in 2000 there existed the question of whether his looming presence was help or hindrance to Al Gore.

It’s yet another sign of Romney’s lack of mooring and touch that he thinks he can get away with this. The idea that Bill Clinton—the man against whom his party attempted a coup d’etat—is now a good guy is stunning. Someone needs to remind Americans that while he was fixing the country, Republicans opposed him every inch of the way, and in the intervening years, they’ve only become more extreme, and Mitt Romney has signed onto every one of their positions. And I know just the guy to do it.