John McCain has thus far defied expectations throughout the primary cycle, and Gallup now says that he has become the most popular candidate in the race. A new poll shows him with higher favorability ratings than the Barack Obama Experience, with significantly lower unfavorable ratings as well. Hillary Clinton, meanwhile, has also begun to show some improvement, with less than a majority detesting her now:

John McCain’s 67% favorable rating is the highest of any of the three major candidates running for president, and ties for his highest in Gallup polling history. …

McCain’s favorable rating matches the 67% he received in February 2000, when he was in the middle of his first run for president. But since that point, McCain’s image in the eyes of Americans has undergone significant shifts. The Arizona senator had favorable ratings in the 57% range as he began his presidential campaign last winter, but as his campaign floundered this past summer, his favorable rating dropped as low as 41%. At that point, many observers had written off the former POW’s campaign. But McCain came roaring back, winning the New Hampshire primary and then clinching the Republican nomination. His current favorable rating represents a gain of 26 points since last summer, including an 11-point increase since he won enough delegates to ensure his nomination on March 4.

Looking at the sample shows another big surprise. Gallup polled adults, not voters or likely voters. Normally, Republicans do more poorly in such a sample, but McCain has scored well among the general population. One could extrapolate that his favorability ratings could go even higher than these numbers if the polling sample was narrowed to more predictive models.

The news for the Democrats is mixed. McCain has an overall +40, and even has a majority favorability rating among self-described Democrats. Obama has a +29, with one-third of all respondents seeing him unfavorably. Hillary has a +9, which sounds worse than it is. In some polls, Hillary has been in negative territory. She’ll take a plus-anything at this point.

Gallup shows that both Democrats have slipped slightly since December, which indicates that the nastiness of their primary campaign has done only minor damage to their prospects — but it could be boosting McCain in comparison. He picked up 11 points in two weeks, while revelations about Tony Rezko and Jeremiah Wright dogged Obama and while Hillary was seen as the primary mover of such stories. It also coincides with Hillary’s “3 AM” ad, in which she asked who America wants answering the call when things go terribly wrong around the world. So far, it looks like the nation has decided that McCain is the better choice.

John McCain is riding high, and he has no reason to dive back into the mess that Hillary and Obama have created. He needs to continue his foreign-policy outreach as he has this week in Iraq and the Middle East, and show the voters which candidate really has the credentials and the experience to take over on Day One. Thanks to the Democrats, he has until August to worry about what the two other candidates have to say about him.