Thursday night's convention speech, the symbolic opening of Barack Obama's general-election effort, will be an important moment in this year's campaign. But no matter what the president says and no matter how well he says it, history likely will record that the 2012 presidential race was transformed not in September but in August -- and not by anything that happened at the Republican National Convention in Tampa last week.
That's because this is no longer a campaign of Mr. Obama against Mitt Romney. It's a campaign of Mr. Obama against Rep. Paul Ryan.
Not in a generation -- perhaps not ever -- has a vice-presidential nominee had such a transformative effect on a national political ticket.
By selecting Mr. Ryan, Mr. Romney did more than signal what kind of administration the Republicans would conduct if they win the White House in November. He did more than catapult Mr. Ryan, until now a cult hero to a tiny enclave of think-tank conservatives, into a national figure and, barring a catastrophic faux pas, a presidential candidate in his own right four or eight years from now. Mr. Romney's choice transformed his presidential campaign into a conversation about Mr. Ryan's personality, character and ideas. The Ryan factor can be captured in one sentence: No serious political thinker of our time motivates Republicans nor irritates Democrats as much as the GOP vice-presidential candidate.
Some running mates have delivered fresh credibility and excitement to a campaign. That's what Sen. Edmund S. Muskie did in 1968, when Vice President Hubert H. Humphrey added him to the Democratic ticket, much as Sen. Joseph I. Lieberman did when he joined Al Gore as his vice-presidential nominee in 2000. Both tickets lost close races and both running mates faltered early in their own, separate presidential campaigns four years later.
But Mr. Ryan did something that neither Muskie nor Mr. Lieberman did. He added a new ideological cast to his ticket. Not even the most ideological running mate of modern times, Henry A. Wallace, who ran with Franklin Roosevelt in 1940, did that.
More recently, the selection of Joseph R. Biden Jr. as Mr. Obama's 2008 running mate didn't reposition the ticket even one degree ideologically. Neither did Gov. Bill Clinton's 1992 choice of Sen. Al Gore nor Vice President George H.W. Bush's 1988 selection of Sen. Dan Quayle. The choice of former Rep. Dick Cheney to run with George W. Bush in 2000 had a dramatic effect on the character of the ensuing Bush administration, but it had no effect on the Bush campaign, except -- and hardly anyone remembers this -- perhaps to soften rather than harden the image of the ticket.
Mr. Ryan's selection, on the other hand, has changed everything -- including future assessments of the impact of a vice-presidential nominee.
Mr. Obama's speech this week will take dead aim at Mr. Romney, to be sure. He almost certainly will portray the GOP nominee as an innocuous opportunist, or worse, knowing that is precisely how many of his fellow Republicans view the former Massachusetts governor. But that no longer matters all that much, at least politically. Mr. Romney's ideas, which members of both parties consider comprehensive but suspect are not genuine, aren't really the point anymore.
None of this is to say that if the Republicans win, Mr. Romney won't be the top dog, make the cabinet choices, sketch the outlines of American foreign policies and be the public face of the nation at international summits. He will. But Mr. Ryan is the Reggie Jackson of the Republicans. He's the straw that stirs the drink.
He also stirs something deep in the modern Republican Party, which for the last six elections has had a rebellious, muscular conservative undertone but each time has nominated for president a conventional Republican, steeped in establishment values and possessing conventional qualifications -- a vice president, two incumbent presidents, two high-profile senators who had both lost earlier nomination fights. Mush that together and you have Richard Nixon, who, remarkably, qualifies on all counts.
Mr. Romney is conventional as well. Like George W. Bush, he served as governor of an important state and, like both Presidents Bush, he was reared by a prominent political father. But Mr. Romney's running mate is a House member, which is unusual but not unprecedented, and Mr. Ryan also is the author of the principal Republican budget proposal, one that takes dead aim at the spending and entitlement programs that are like the weather: Everyone talks about them but nobody does anything about them.
Much of last week's GOP convention was designed to burnish the image of Mr. Romney, to add human dimensions to his profile, to portray him as an experienced job creator who can do what Mr. Obama has failed to do: trim unemployment substantially and get the economy moving. Seeking to make the public comfortable with an alternative to the incumbent is standard fare for a challenger's convention.
But what is different in 2012 is that the table-setting for the fall campaign has been altered. Nobody is talking much about Mr. Romney's ideas. People are talking about Mr. Ryan's. Nobody is saying there is Republican excitement over Mr. Romney. People are talking about Mr. Ryan.
This week the Democrats will spend plenty of time demonizing Mr. Romney. They'll say he is an outsourcer, a heartless private-equity wizard whose eyes turn to the bottom line and away from the human costs of efficiency, a bloodless executive lacking in the common touch.
But the ideas the Democrats will demonize won't be Mr. Romney's but Mr. Ryan's. He's the guy who makes Republican hearts flutter -- and who gives Democrats heartburn.
Other running mates have done that, of course. Gov. Spiro Agnew of Maryland performed that duty in the 1968 campaign and then in the vice presidency. But he had no real ideas of his own. He had a kind of Murderer's Row of the speech-writing craft (William Safire and Patrick J. Buchanan) but what he pedaled was invective, not ideology. This is what sets Mr. Ryan apart. He has a mind of his own, and ideas of his own.
Since the spring the political class has wondered what might happen when Mr. Obama and Mr. Romney meet for a debate. Onetime Jimmy Carter speechwriter James Fallows even filled eight Atlantic Monthly pages this month speculating on this looming meeting of titans.
But that may not be the main event. The real fun will occur Oct 11. That's when Mr. Biden and Mr. Ryan face off in front of a national audience. Skip it and you'll likely miss the biggest moment of the 2012 campaign.
David M. Shribman is executive editor of the Post-Gazette (firstname.lastname@example.org, 412 263-1890). Follow him on Twitter at ShribmanPG.