There is a good reason why John McCain's campaign is having some trouble with truthiness these days.

McCain's claim to be a "maverick" rests on the liberal positions he took during the days when he openly fought with Republican leaders and the party's conservative base.

Because he cannot very well motivate Republicans by reminding them of the times he and they have quarreled, he has to distract and dissemble.

Think of the breaks that McCain has made with Republican orthodoxy.

He joined liberal Russ Feingold and pushed for campaign finance reform—conservatives loathed it.

He was a soldier with Al Gore in the fight against global warming—the oil industry and free market think tanks opposed them.

He and Ted Kennedy helped write a humane immigration bill—the GOP nativists despised him.

He joined with Bob Byrd and six other Democrats to kill a Senate Republican plan to pack the federal judiciary—abortion opponents were furious.

He sided with Tom Daschle's Democrats and voted against the Bush tax cuts—the antitax groups fumed.

He took on House and Senate Republicans who were trying to bring pork barrel spending to their states—the GOP majority went ballistic.

And he aligned himself with liberal groups like People for the American Way, when denouncing the clout of "evil" evangelical political leaders.

Actions like these endeared McCain to left-leaning journalists and independent voters who were alarmed by the influence of GOP social and religious conservatives. Even though he was voting with his fellow Republicans 85 percent of the time, McCain built a reputation as a maverick.

Yet, as they prepared for the 2008 presidential race, McCain's advisers knew they would have to woo those conservatives. And so they launched what they called "McCain 2.0" in 2007.

When Jon Stewart asked McCain last year, "Are you going into crazy base world?" the celebrated maverick acknowledged, "I'm afraid so."

McCain flip-flopped on the Bush tax cuts. He abandoned immigration reform. He reached out to Jerry Falwell and other religious conservatives.

It wasn't enough. And so, in a move that even one of his longtime advisers conceded (in a remark captured by an open microphone) was disturbingly "cynical," McCain gave the base Sarah Palin.

Palin was a smart pick. She juiced up the faithful and pleased the preachers, and the hoopla of her nomination eclipsed the inherent flaws of McCain 2.0.

But time moves on, and the Palin balloon has lost a little air as Americans have discovered she is a politician—given to flip-flops, fibs, abuse of power, wasteful spending, and the rest of the familiar roster of venal sins that come with the territory.

The focus is moving back to McCain, who has still not resolved the contradictions of his candidacy.

Is he truly a maverick who, like his self-proclaimed hero, Teddy Roosevelt, will govern as a progressive? Or will he be beholden, as folks like James Dobson and Rush Limbaugh insist, to the conservative base?

So far, the main "maverick" actions that McCain has promised as the next Republican president are to trim nonmilitary Democratic spending and continue the Iraq war. You can't get more conventional than that.

And even that message has been somewhat undermined by disclosures that Palin was a champion of those costly federal earmark projects she has lobbied for in Alaska—where, you know, you can see Russia.

At this point, McCain has taken the obvious way out—launching a series of distracting attacks on Barack Obama, with slim regard for truth.

The ads have spurred a backlash, the consequences (or lack) of which may well decide the election.

For 18 months, Obama has wagered all his chips on the (quaint? idealistic? brilliant?) idea that the American people are tired of the same old sleazy and divisive politics. McCain has now chosen to bet against him.