A good read today -- up on the front page of course -- from Rich Lowry on the possibility and the consequences of McCain choosing Lieberman:

To placate Republicans and maximize the political impact of his selection, Lieberman would have to join the ticket as part of a McCain pledge to serve just one term. Both McCain and Lieberman would promise not to run for president in 2012, removing any possibility of Lieberman becoming a successor or putting his imprint on the Republican Party. Their administration would be above electoral politics, a high-minded exercise in competent governance and bipartisan compromise.

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.

As Lowry notes, picking Lieberman whatever the conditions is a "desperate move," one McCain has no need to make right now. And desperate moves aren't sure things. Forget the Republican base for a second, there's no knowing how moderate and independent voters would take a McCain-Lieberman ticket. They could very well reject the notion as a gimmick and hand the election to Obama in a landslide.

And what about conservatives? The one thing we heard throughout the primaries but rarely anymore is Ronald Reagan's name. Conservatives have accepted the idea that a McCain presidency won't do very much for conservatism. Indeed, with the obvious exception of foreign policy, McCain isn't even trying to argue that he will. The best conservatives hope for out of this election is to keep Democrats out of the White House, and thus from controlling all the levers of power. The next Reagan would have to wait.

Conservatives had hoped, however, that McCain might speed the process by tapping a genuine conservative who could potentially rejuvenate the moribund Republican brand and be ready to lead in 2012 or 2016. But even that hope is fast fading, as few on McCain's short list are movement conservatives.

But, back to Lowry's point, would a McCain-Lieberman pledge to serve just one term be a deal conservatives are willing to accept? And not only that, would the base be excited enough to do the necessary GOTV efforts that were so instrumental in Bush's 2004 victory?

To answer both questions with a yes, a McCain-Lieberman ticket would have to make foreign-policy its exclusive theme. (How a McCain-Lieberman could avoid answering domestic-policy questions is an entirely different problem with no good answer.) And despite the threats from Iran, the crisis in Georgia, the ongoing Iraq war and the overall war on terror, I think it would be next to impossible for a McCain-Lieberman ticket to turn the public's focus away from the economy.