You know politicians are serious when they move from campaigning to governing. Something like that may be happening on the Republican campaign trail — but, unfortunately, not at the Obama White House.

Campaigning clearly carried the day for Newt Gingrich in South Carolina, where he beat Mitt Romney by a 40 percent–to–28 percent margin. It’s generally agreed that Gingrich clinched the race when he reacted angrily to questions by Fox News’s Juan Williams and CNN’s John King.

Both times Gingrich got standing ovations. But not for how he’d govern. His platform can be summed up in a bumper sticker a Washington lawyer printed to buck up George H. W. Bush’s hapless 1992 campaign: “Annoy the media — vote for Bush.” It was fun but didn’t win many votes.

South Carolina Republicans got a charge out of imagining how Gingrich would rebuke Barack Obama in the Lincoln–Douglas debates he’s been proposing. Except of course Obama would never agree to that format.

In the Monday debate at Tampa, Fla., Romney came back hard at Gingrich, saying that he had been ousted as speaker by his own party and that he had to resign “in disgrace.” Gingrich complained afterward about the ban on applause and said he might not show up for later debates with a similar ban (it is imposed in the fall debates).

What’s important here is that Romney went after Gingrich for the way he governed. Gingrich cites, with a little exaggeration, significant things he achieved as speaker — welfare reform, holding spending down, tax cuts.

But his quibbling with Romney over the timeline of his ouster as speaker misses the point. Many former colleagues, including Rick Santorum in the last two debates, have criticized him as an erratic and unsteady leader. These conservatives are troubled by the way he governed.

And Gingrich was not helped by the interchanges on his work for Freddie Mac — which along with Fannie Mae was heavily responsible for creating the housing bubble that dragged down the economy when it burst — or by the way he defended his advocacy of the Medicare prescription-drug program, an expansion of entitlements opposed by many conservatives.

Romney’s critics have hit the former governor for not doing much to advance the conservative cause.

They have something of a point. But Romney was able to cite a conservative fiscal record in Massachusetts despite an 85 percent Democratic legislature. And he might have pointed out that, if he is elected president, he will likely govern with a Republican Senate and Republican House.

Romney is now burdened with an economic platform that has rightly been called timid, with only small tax cuts. But the fiscal plans of other candidates are subject to attack as leading to enormous budget deficits when scored by neutral arbiters.

Romney’s vaguer call for broadening the tax base and lowering tax rates, as in the bipartisan 1986 tax reform and as advocated by the Bowles-Simpson commission, is something that could actually happen. He hasn’t been specific, but neither was Ronald Reagan in the election leading up to the 1986 law. Perhaps naïvely, I think Romney is thinking seriously about governing.

Barack Obama isn’t, and that’s one thing Republican candidates might want to bring up in the next debates. Obama rejected the Bowles-Simpson recommendations out of hand, and he seems untroubled that the Democratic-majority Senate hasn’t produced a budget in 1,000 days.

That’s contrary to the requirements of law, as is the administration’s delay in sending up its own budget three years in a row.

But this is a president who flouts one law after another. He made recess appointments when the Senate was not in recess, in violation of the Constitution; one of the appointments was to a position whose occupant, according to a law Obama himself signed, cannot act without Senate confirmation.

He vetoed the Keystone XL pipeline on environmental grounds that the law says could not be considered. His policy on whether religious organizations can require employees to share their beliefs was swatted down by a 9–0 vote of the Supreme Court.

What we see is a president who is in pure campaign mode and cavalier about the rule of law, with policies — higher taxes, environmental restrictions, more stimulus spending — poorly suited to current needs.

The Republican candidates are struggling fiercely with one another. But a candidate who concentrates less on denunciation and more on governing could have an advantage in the fall over an incumbent who is doing more denouncing than governing himself.

— Michael Barone is senior political analyst for the Washington Examiner. © 2012 The Washington Examiner.