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.