St. Paul, Minnesota—Last night was a victory for a historically marginalized group whose contributions have too often been downplayed and overlooked, a group that has not received equal credit for equal work: vice-presidential candidates.

All this week, political analysts have been reminding us that vice-presidential running mates don't usually make much difference in presidential races, and there is good historical data to back this up. Geraldine Ferraro was initially well-received, for example, and Dan Quayle wasn't—yet Mondale lost in 1984 and Bush won in 1988. But as they say, historical trends are likely to continue until they don't.

After her speech last night—the text is here, but watch the video here—I suspect that in this election, John McCain's selection of Sarah Palin will fundamentally change the contest.

Until last night, I thought that Barack Obama was a charismatic politician who could give a really good speech. I guess it's been so long since we've seen the real thing that the standard has been set pretty low. Sarah Palin showed us what we've been missing.

Obama is very polished and intelligent, and while he is far better than most politicians at faking sincerity, there is still something detached in his delivery, a self-conscious formality that keeps him from being completely genuine. Sarah Palin, by contrast, managed to look both supremely poised on stage and completely comfortable. She delivered her lines flawlessly, but rested her arm almost casually on the podium as she spoke—an extraordinary self-assurance for a virtual unknown delivering this year's most highly anticipated, high-risk political speech. And when she saw banners in the audience reading "Hockey Moms 4 Palin," she seamlessly broke from her prepared text to ad-lib a joke. This is one of the most difficult things a speaker can do, and trust me, you don't want to watch Hillary Clinton attempt it.

The joke? "What's the difference between a pit bull and a hockey mom? Lipstick." At this last word, she gestured toward her own mouth.

A "pit bull with lipstick" is a good analogy for the polemical portions of her speech. She effortlessly accomplished another one of the most treacherous tasks a politician can attempt: she delivered withering political attacks and pungent jibes at her opponents without seeming shrill or mean-spirited. (Contrast her, in this regard, to Rudy Giuliani's speech earlier in the evening. He had some good lines, but he delivered them with a jabbing finger, an angry face, and a tense shout, all of which combined to make him seem petty.)

The polemics came one after another, and each hit home.

I guess a small-town mayor is sort of like a "community organizer," except that you have actual responsibilities.

I might add that in small towns, we don't quite know what to make of a candidate who lavishes praise on working people when they are listening, and then talks about how bitterly they cling to their religion and guns when those people aren't listening. We tend to prefer candidates who don't talk about us one way in Scranton and another way in San Francisco….

[L]istening to [Obama] speak, it's easy to forget that this is a man who has authored two memoirs but not a single major law or reform—not even in the state senate….

In politics, there are some candidates who use change to promote their careers. And then there are those, like John McCain, who use their careers to promote change. They're the ones whose names appear on laws and landmark reforms, not just on buttons and banners, or on self-designed presidential seals.

Palin delivered these one-liners with a smile, a note of cheerfulness, and a mischievous twinkle in her eye. She didn't convey a sense of being bitter or angry at her opponents, the way Giuliani did. Instead, she seemed to be amused by their foibles. This is the way Reagan attacked opponents—the smile, the shake of the head, and "there you go again"—and the American people love it. They like a "happy warrior" who is comfortable with the give-and-take of political battle, but who doesn't seem to take it too personally.

Slate's John Dickerson sums it up nicely when he writes: "It was clear Palin was having fun, and it's hard to have fun if you're scared or a lightweight."

This is one of the reasons Palin's performance will alter the race. When McCain introduced Governor Palin and the media began picking apart her record and dredging through her family's messy soap-opera, there was some question whether McCain had made a hasty and reckless decision in choosing a virtual unknown. Now he looks like a genius for discovering a major new political talent.

But Palin's speech was not just a showcase for her personal charm. Her one-liners and her fresh, outsider's appeal reinforced the theme of the speech, which was that she and John McCain would be political outsiders who would bring reform and change to Washington. In essence, it was an attempt to beat Barack Obama at his own game.

Here is her basic sales pitch:

Americans expect us to go to Washington for the right reasons, and not just to mingle with the right people….

The right reason is to challenge the status quo, to serve the common good, and to leave this nation better than we found it….

This was the spirit that brought me to the governor's office, when I took on the old politics as usual in Juneau, when I stood up to the special interests, the lobbyists, big oil companies, and the good-ol'-boys network….

I came to office promising major ethics reform, to end the culture of self-dealing. And today, that ethics reform is the law.

While I was at it, I got rid of a few things in the governor's office that I didn't believe our citizens should have to pay for.

That luxury jet was over the top. I put it on eBay.

And yes, that last part really is true.

Barack Obama was supposed to be the fresh face who would "change" Washington. But after a summer in which he hired Washington insiders by the dozen, chose one of them as his running mate, and made calculated moves to the center on one issue after another, he now seems like a conventional politician more concerned with his own ambition than with any kind of ideal. Obama squandered his advantage, and now Palin has just stolen the "change" and "reform" message that appeals to the independent swing voters who are likely to decide the election.

Palin's performance last night was so good that I began to hear some concerns this morning that she might overshadow John McCain. I disagree. The person she will actually overshadow is Obama. As this long presidential race enters a surprisingly brief home stretch—the election is exactly two months way—Palin will be the more interesting and refreshing personality, she will get more attention from the press, and she will attract more independent voters.

And the effect of last night's speech is not just that it will attract independent voters. It will also give John McCain the one thing he hasn't had up to this point: the enthusiasm of his base. He turned off free-marketers by embracing economy-choking energy rationing; Palin brings them back with her spirited advocacy of oil and gas exploration. The religious right was wary of McCain; Palin's anti-abortion stance and religiosity brings them back.

I wrote recently about how Palin supplies the two legs of the conservative coalition that McCain was missing. Jack Wakeland responded with a good formulation of the sense-of-life impact of this ideological re-unification: "Republicans from different branches of the party are happy to feel a little bit like they've all been put back together again."

This was my sense of the audience reaction in the Excel Center last night. The Republican base wanted to like Palin and hoped that they could like her—and they were ecstatic to find that she exceeded their expectations. That's something that hasn't happened to Republicans in a long time. It is too mild to say that the conservative base emerges from Palin's speech "energized"; they will now be fanatical in their support for the party's ticket. And that will translate into hundreds of thousands of volunteers to make phone calls, goad their friends, and staff get-out-the-vote drives in November.

Fred Barnes is right when he calls Palin "a natural, gifted with the ability to connect with people in a way that few politicians can and to perform under extreme pressure. She has star quality." He is also right when he notes that "Republicans haven't seen anyone like Palin emerge from their ranks since Ronald Reagan first attracted national attention in 1964."

And here's where we need to throw a little bit of cold water on the glowing evaluations of Palin's speech. The speech that launched Reagan's career was far more substantive. It talked about a "time for choosing" between freedom and slavery, between standing up to the Soviets and appeasing them. It was a speech about basic principles. There was nothing half so profound in Governor Palin's speech

As you can tell, I really do like Sarah Palin; I have an awful weakness for tough, spunky, spirited women. But her personal qualities, while certainly relevant to her candidacy, are not decisive. We have to look at the actual policies she is likely to support. On that question, we still have not heard much from her own mouth.

What I can say so far is that she substantially mitigates my worst fear about McCain—but she adds a new fear that was not nearly as strong before.

My greatest fear about McCain was that he would ensure the passage of "cap-and-trade" energy rationing. But House Republicans have begun agitating for an opposite policy of increased oil drilling—and Palin's selection elevates that issue to the center of the McCain campaign.

On the other hand, McCain has not previously been noted as a crusader for the religious right. While Palin did not say anything last night about her consistent and radical anti-abortion stance, her presence on the ticket could now elevate a religious agenda to the center of the McCain campaign.

What we know already is that Palin will be the rare vice-presidential candidate who makes an important difference in the race. But we don't yet know enough about what effect she will have on the ideological direction of a potential McCain administration.

We can definitely say that she is likely to help McCain in the political horse race—but we cannot quite say whether it should help him.

Stay tuned.