The toxic effects of right-wing extremism in Washington were vividly on display during the payroll-tax fiasco — even to the right wing. On the campaign trail, though, those lessons are being ignored. The leading Republican presidential candidates are overtly competing for the title of Most Conservative, distorting their own records and advocating increasingly radical positions.

Candidates often move to the ideological edges to win a primary, because that’s where the primary voters are, but the frenzied efforts of Mitt Romney and Newt Gingrich are particularly hard to watch. Neither has a record as a dogmatic conservative, and they are competing with candidates like Rick Santorum and Michele Bachmann who have much longer and more consistent conservative records. That makes their rush to the right all the more desperate and convoluted.

Last week, Mr. Romney blasted Mr. Gingrich as “an extremely unreliable leader in the conservative world,” citing specifically Mr. Gingrich’s criticisms of Paul Ryan’s Medicare plan and his appearance with Nancy Pelosi in a commercial against global warming. Mr. Gingrich, in turn, claims he’s “a lot more conservative” than Mr. Romney.

Real conservatives, in their columns and magazines, say neither of them qualifies, noting that both have previously called themselves “progressives” when appealing to very different audiences than the ones in Iowa and New Hampshire. Mr. Romney once supported abortion rights, though now he says he has changed his mind. Mr. Gingrich fiercely opposes the government’s role in the housing market, but worked for Freddie Mac. Both have supported an individual mandate for health insurance, as well as the TARP bailout of Wall Street.