We have known what Barack Obama’s message is for a year: change. Change Washington’s political culture, change the way we engage our enemies, change the tax structure, and change reliance on a largely private health care insurance system. His countermessage: John McCain is against change and wants more of George W. Bush’s policies.

So what is McCain supposed to do about this? For starters, he really does need an over-arching theme. Victory in Iraq and preserving tax cuts are not a theme: they’re policy positions. George W. Bush had a theme–compassionate conservatism–which turned out to be not much of either, but it was a theme. And biography, no matter how compelling, is also not a theme. Running against an extreme liberal with a grab bag of wacky associates and no record of accomplishment could be an asset. But, again, it’s not a theme.

When McCain comes up with a theme, one he can explain in a sentence (a few words would be better), we will know that he has an actual strategy to beat Barack Obama. In the end, voters have to vote for something: Something (however flaky) will beat nothing every time.