NOT ONCE but twice voters have been treated recently to extraordinary displays of the volatility of politics: former Vermont Gov. Howard Dean's heart-stopping plunge from Democratic front-runner to primary shutout, and the simultaneous free-fall of the president he seeks to unseat.
Less than two weeks after President Bush confidently delivered a status quo State of the Union address crafted to appeal almost exclusively to his conservative Republican base, he was so desperate for a forum to defend himself he voluntarily entered the gladiator pit of Sunday morning talk television.
Presidents rarely lower themselves to engage on that level. But after weeks as the Democrats' main punching bag, Mr. Bush suddenly found himself losing ground in the swing-vote center - thanks in part to embarrassing revelations about the weapons of mass destruction used to justify his military strike on Iraq and about the deficit-bloating Medicare expansion intended as the centerpiece of his domestic accomplishments.
Whether or not the president's uneasy performance helped him reconnect with erstwhile admirers, Mr. Bush at least succeeded in articulating what will be a central issue of this campaign: his judgment.
He used the phrase again and again to describe how he made the decision to topple Saddam Hussein from power, believing apparently erroneously that Iraq had WMD. Even without them, the dictator posed a threat, Mr. Bush said, because he was a "madman" who had used banned weapons in the past.
Context is critical, Mr. Bush said. "I'm dealing with a world in which we have gotten struck by terrorists with airplanes. ... The worst nightmare scenario for any president is to realize that these kind of terrorist networks had the capacity to arm up with these deadly weapons and strike us."
Nobody pretends such decisions are easy. Most of Congress - including several Democratic challengers - voted to give the president a blank check, then stood back and watched to see what he did with it. That's why the commander in chief's personal judgment is so vitally important.
But it was hardly reassuring to hear Mr. Bush explain that he ordered the military strike in part to prove that the United States follows through on its threats.
Cutting taxes while fighting a war on two fronts also reflects questionable judgment, and has come back to haunt the president by ballooning the deficit past the point of acceptability for some GOP House members. Mr. Bush says Congress can reduce the red ink by squeezing domestic social programs, though that's not where the money is, and yesterday he dusted off the classic GOP charge that Democrats want to raise taxes to pay for bigger government. Is that worse than not paying for it, as he has done?
History suggests polls will continue to rise and fall throughout the campaign. The gauge to watch is judgment.