To assuage Republican fears of a Harrison/Tyler scenario, Lieberman would have to pledge, if he were to ascend to the presidency, to appoint constitutionalist judges and honor McCain's domestic priorities.

The possibility of a one-term pledge is actively bruited around McCain headquarters. The thinking is that there is no more dramatic way to augment his standing as a different kind of a politician and capture the public's frustration with politics as usual. (Realistically, at age 76, McCain might not want to run for re-election anyway.)

Lieberman is the natural complement for a one-term pledge. He is a politician with no aspirations in the GOP, with little future in his own caucus, and with a long record of bipartisan cooperation. If McCain decides the only possible path to victory is a risk-taking, unconventional one, Lieberman is his man.

The ticket would be the American equivalent of Israel's centrist Kadima party. It would represent the Republican Party's acquiescence to its exile in 2008, although perhaps for only four years and not as far into the outer darkness as if Obama wins. The executive branch would at least be led by two hawks on the war who would check the worst excesses of the Reid-Pelosi Congress.

If they were elected. And there's no guarantee of that. A McCain-Lieberman ticket might have an unbecoming pleading quality -- please, we're not really Republicans, so let us in for just 1,461 days. The ticket would make McCain, the experienced hand, the steward of a campaign verging on the gimmicky. Finally, how could Lieberman follow McCain's domestic priorities when McCain himself doesn't always seem to know what those are?

McCain-Lieberman is a more desperate move than McCain should feel compelled to make right now. But check back after Denver.