Now Mitt’s in the muck. Now we’re in the muck. It’s kind of fun for insiders. But for those who will decide the election, the appeal may be hard to see. With the Romney and Gingrich camps going thermonuclear on each other—Newt tarring Mitt with Swiss and Cayman Island bank accounts—the fallout could damage more Republican infrastructure than just these candidates.

Many of the dark charges that Messrs. Gingrich and Romney are launching at each other are real, or real enough. Newt Gingrich has a serious Freddie Mac problem. It is also disconcerting that so many former, respected House colleagues are critical of his leadership and political character. Mitt Romney’s inadequate answers to Rick Santorum’s point-by-point critique of his health-care plan are (still) a problem. The Romney tax return screams “tax reform,” but he only whispers the phrase. The Bain bonfire burned both Messrs. Gingrich and Romney—the former for doing it and the latter for letting it fester in public.

All this might have been survivable in the old era, after the nomination was secured and the “politics” evaporated. But new media magnifies and extends all the dark charges and bad odor. We are all marinating in it. It sticks. Republicans seem to think these primaries are a family fight. But independents, now perhaps 40% of the electorate, are also in the stinky marinade. The ABC-Washington Post poll just recorded Mr. Romney’s unfavorable number rising 15 points in two weeks. It now matches Newt’s awful unfavorables.