DENVER — Republican presidential candidate John McCain decided on a running mate early Thursday, and one top prospect, Minnesota Gov. Tim Pawlenty, abruptly canceled numerous public appearances.

The Arizona senator will appear with his No. 2 at an Ohio rally on Friday, aides said, though they provided no details on McCain's pick.

Without explanation, Pawlenty called off an Associated Press interview at the last minute, as well as other media interviews in Denver, site of the Democratic National Convention.

Others believed to be in contention for the No. 2 slot on the GOP ticket included former Massachusetts Gov. Mitt Romney, who was meeting with donors throughout California, and Democrat-turned-independent Sen. Joe Lieberman of Connecticut, who was vacationing on New York's Long Island.

Former Pennsylvania Gov. Tom Ridge, too, was still a possibility, as was the idea that McCain would choose a dark horse from any number of names that have circulated.

Fueling speculation that McCain would choose either Pawlenty or Romney or another conservative Republican, two GOP officials said they believed McCain had picked a traditional candidate. They based their conclusion on the fact that the campaign, which once had put the party on notice to prepare for the possibility of an unconventional candidate, does not have preparations in place to curb the fallout from a right flank that certainly would revolt if Ridge, an abortion-rights backer, or Lieberman, a former Democrat, was on the ticket.

If he knew McCain's decision, Pawlenty gave nothing away when he arrived back at Minneapolis-St. Paul International Airport shortly after 5 p.m. Thursday. "This is Senator McCain's decision and his announcement and we all want to be respectful of his desire to have the chance to announce it himself," Pawlenty told KSTP-TV.

In front of Pawlenty's private home in Eagan, a southern St. Paul suburb, more than two dozen people — including a man wearing a Barack Obama T-shirt — mingled and watched the number of satellite TV trucks grow. A pair of media helicopters flew above, but it appeared no one was home.

At the governor's mansion in St. Paul, eight to 10 journalists were on stakeout. Two young girls walked out briefly, then went back into the mansion, which is protected by iron gates. Pawlenty has two young daughters.

McCain, for his part, was uncharacteristically silent.

As he and his wife, Cindy, boarded a plane in Phoenix bound for Dayton, Ohio, reporters shouted a barrage of questions at the senator about whether he'd made up his mind. McCain wasn't biting. He flashed a double thumbs-up and boarded the plane.

Earlier, he played coy.

In an interview aired Thursday morning, McCain said he still hadn't made up his mind. Far from quieting speculation, this only fueled it as he sought to siphon attention from Democrat Barack Obama's acceptance of the presidential nomination in Denver.

He told KDKA NewsRadio in Pittsburgh in an interview taped Wednesday: "I haven't decided yet so I can't tell you."

McCain, who spoke with the radio station from his home in Arizona, told people late Wednesday that he wasn't going to make a final decision until after he talked with his wife. She has been in the country of Georgia this week and returned sometime at nightfall.

With both the eventual pick and the effort to keep buzz alive beforehand, McCain's campaign hopes curb any uptick in polling that Obama might get from his convention and to create momentum heading into the gathering of GOP delegates for McCain next week in St. Paul, Minn.

Pawlenty, in Denver earlier to criticize Democrats on McCain's behalf, canceled without explanation an afternoon roundtable interview with the AP as well as other media interviews. Questioned about the vice presidential selection earlier, Pawlenty would only say that he is to be in Minnesota on Friday for the state fair.

Romney, who had played the GOP attack-dog role earlier in the week at the Democratic convention, left his beachfront San Diego home Thursday morning with an overnight bag. His son, Matt, said Romney was headed to an unspecified location in the state. Asked about being vice president, the elder Romney said: "I don't have anything for you right now."

Ridge was at his suburban Washington, D.C., home. Asked by an AP photographer as he took out the trash if he had any travel plans for the day, Ridge smiled and said he didn't.

One Lieberman aide said there has been no indication he is the choice. For instance, no staff have been called to join him at his vacation site.

For months, McCain's vice presidential search process has been kept closely held by a small group of his advisers. But details have been trickling out this week.

This includes word from two Republicans that McCain met with his senior advisers in Arizona on Wednesday to discuss the pick, conflicting information about whether or not he had settled on a choice, and the campaign's announcement it would air a one-evening-only TV ad in battleground states around when Obama will be giving his prime-time acceptance speech.

Turns out the ad has nothing to do with the vice presidential choice, bearing only a simple message for Barack Obama: "Job well done."

Associated Press writers Glen Johnson in Boston, Mike Glover in Phoenix, and Andrew Miga and photographer Scott Applewhite in Washington contributed to this story.