Karl Rove reminds us that party conventions, despite the excess of artifice, must have a central message. I think his advice is largely, but not entirely, sound when it comes to John McCain. He is on the mark in counseling McCain to demonstrate domestic policy prowess and to stress his bipartisan bona fides. But I think he goes astray when he suggests

Mr. McCain’s warrior ethic makes it difficult for him to share his interior life, though his conversation with Rick Warren did provide moving glimpses into it. To win, Mr. McCain will need to show more.

Emotive self-revelation is not McCain’s thing. The last thing Republicans want to do is to introduce mawkish emotion and overblown egotism into their own candidacy. That’s for the other guy. Let McCain be humble and restrained.

As for Obama, I think Rove again gets it entirely right when he explains:

Mr. Obama, on the other hand, needs to reassure Americans he is up to the job. Voters recognize he represents change, yet they are unsettled. Does he have the experience to be president? There are growing concerns, which the McCain campaign has tapped, that Mr. Obama is an inexperienced celebrity-politician smitten with his own press clippings . . . Mr. Obama’s performance this summer has added to voter doubts, putting a large burden on his acceptance speech. There are challenges in a speech staged with 75,000 screaming partisans at INVESCO Field. Will it deepen the impression that he’s more of a rock star than a person of serious public purpose, or can Mr. Obama have the serious conversation he needs to reassure Americans?

It is ironic that the candidate the Left has lionized as a great intellectual must now prove that its candidacy is “about important answers” and not merely about the “change we’ve been waiting for.” Unlike the Democrats who seem fixated on atmospherics and proving their candidate is a patriot, Rove suggests (rightly, I think) he would do better to demonstrate that he is not a policy lightweight and is serious about specific policy objectives. After all, if sympathetic bloggers can’t figure out where he stands on economic policy how is the public going to? Does he have principles? And, if so, are they something more than recycled liberal orthodoxy?

But one thing is indisputable. Especially in a race this close, as Rove points out, a convention “can still shape, and maybe even alter, an election.”