Democrats are wrangling over House leadership posts—for another day or so—but the party with the most serious divisions and challenges coming out of the 2010 election cycle is the Republicans.

Who says?

John McCain.

The man the Republicans ran against Barack Obama two years ago is hailing the 2010 election results as evidence of a "revolt"—and he said the fire could soon turn on the GOP.

Just reelected as a born-again right winger—running with the backing of his 2008 GOP VP nominee Sarah Palin and often sounding more Tea Party than the Tea Partisans—McCain now says that his party is in danger of losing the confidence of the American people.

Republicans will lose if they do not abandon their Washington insider ways on budget issues—which he characterized as "corruption"—McCain told the Wall Street Journal’s CEO Council session this week.  "I predict to you that unless Republicans act in response to the American people, they will reject Republicans. If Republicans use their power in the fashion, frankly, we did previously when we were in the majority, then I think you will see an emergence of a third party in America."

McCain’s not the only Republican talking about a split. Palin made headlines in October by asking, "Why not a third party?" South Dakota Senator John Thune, a McCain ally, has said: "I will say this: If we do not govern according to our principles and if we don’t follow through on the things we say we’re going to do, I think there will be a third party in this country."

But McCain pushed the prospect further than Palin’s fellow third-party speculators, going so far as to suggest that he fully understood the notion that the GOP is "on probation."

There’s nothing unreasonable about voter distrust of Republicans, McCain said. "They have every reason to be skeptical, because when we were in charge, we let spending get out of control," he said of the period from 1995 to 2007 when the GOP controlled the House and—for all but a brief period—the Senate. "We engaged in earmarking and pork-barreling, which is corruption—I’ve seen it with my own eyes."

Some speculated that McCain would quietly serve out a last term in the Senate after losing the presidential race to Barack Obama and then facing a nasty primary challenge in his 2010 re-election run.

Don’t believe it.

McCain is still going for the headlines. And if Republicans don’t watch out, he could yet be what he was for most of the previous period when they controlled the Senate: the loudest and most consistent inside-the-party critic of GOP orthodoxy. Indeed, Republican leaders may soon be reminded of why they always hated McCain—especially if he keeps stoking the third-party talk.