Gov. Tim Pawlenty is expected to be in Denver this morning, making the rounds of TV talk shows to lambast Barack Obama on the day the Illinois senator will accept the Democratic nomination for president.

The high-visibility mission is the latest stop in a whirlwind campaign swing that for several days recently sent Pawlenty barnstorming for Republican candidate John McCain across the battleground states of Ohio and Pennsylvania. It culminates months in which Pawlenty's national profile has risen amid speculation about his chances of being chosen as McCain's running mate.

Pawlenty has plenty of company on McCain's so-called short list of potential running mates. The choice is expected to be announced Friday morning, either propelling Pawlenty into the full glare of the national spotlight or returning him to the relative shadows.

Which will it be? Neither McCain nor Pawlenty is offering any clues.

Wednesday, a rare day in which he was in Minnesota, Pawlenty visited the State Fair, making the rounds of radio and TV stations, drawing questions about his veep prospects that he declined to answer.

When asked if he has spoken with McCain at all in the past week, Pawlenty initially replied, "About what?" He later said, "I don't address questions that relate to vice president issues."

He added that he was "planning" on being in Minnesota Friday for his weekly radio show and scheduled to be in the state Saturday and Sunday.

Earlier this week, appearing on the Tonight Show, McCain was asked about Pawlenty by host Jay Leno. "He's a great young man," McCain replied. "A great governor of his state."

Among those also being considered for running mate are former Pennsylvania Gov. Tom Ridge and former Massachusetts Gov. Mitt Romney, who filled the Denver attack role until today.

Like others on the short list, Pawlenty would bring political assets and liabilities to a GOP ticket. But clearly his longstanding loyalty to McCain boosts his chances.

In the darkest days for McCain's bid in the winter of 2007, when he was short on cash and slumping in the polls, Pawlenty, national co-chair of the campaign, gave him a helping hand. He traveled to Iowa and joined McCain at stops in Des Moines, Ames and Mason City.

At 47, Pawlenty is a youthful complement to McCain, who turns 72 Friday. Pawlenty belongs to a Christian evangelical church and opposes abortion, characteristics that would make him more appealing to the conservative wing of the party than Romney, a Mormon, and Ridge, a supporter of abortion rights.

With blue-collar roots in South St. Paul, Pawlenty could counter Democratic suggestions that McCain and his wealthy wife, Cindy, are out of touch with average Americans, and perhaps do so more effectively than Romney, a wealthy businessman.

As a Republican governor who prevailed in a swing state in 2006, a strong year for Democrats, Pawlenty could help McCain in Minnesota and other Midwestern states where the race might be tight.

Demonstrated loyalty

And those who have followed McCain's career say the Arizonan places high stock in loyalty, and Pawlenty has demonstrated it in the past two years, campaigning for him through good times and bad.

"I just wanted to get on the bus with him, spend some time with him, offer whatever advice I could," Pawlenty said during the 2007 Iowa trip. McCain at the time declared the governor "a leader of the new generation of the Republican Party."

But other factors could dissuade McCain from picking Pawlenty.

Polls provide conflicting data on whether Pawlenty would make a crucial difference in Minnesota. His victory in 2006 was narrow and he didn't win a majority of the vote in either of his two elections as governor.

The state's 10 electoral college votes pale in comparison with the 17 held by Michigan, where Romney has roots, or the 21 in Pennsylvania, Ridge's state.

Pawlenty is not well known to the national public; Leno mispronounced his name when asking McCain about him.

Faint praise

And McCain's Tonight Show description of Pawlenty as "a great young man" struck one political observer as faint praise, revealing possible doubts about whether he is qualified to suddenly take over as president if needed.

"Maybe McCain's not sure that [Pawlenty's] ready on Day One, if he's saying he's an impressive young man," said Steven Schier, professor of political science at Carleton College, who watched the show.

Pawlenty's lack of national office experience stands in contrast to that of Delaware Sen. Joseph Biden, who was picked last week to be Barack Obama's running mate. Biden has more than three decades of experience in Congress and is considered an expert on foreign affairs.

Former Minnesota Gov. Al Quie, a Republican, said that while Pawlenty would be at a disadvantage to Biden in a debate on foreign affairs, on domestic issues "I think he can hold his own." As for Pawlenty's qualifications to take over as president, Quie said: "He has within him, I think, the qualifications to do it."

Another former Republican governor, Arne Carlson, wrote in a blog in early August that Romney, who helped engineer health-care reform in Massachusetts, was "the best over-all bet" for a running mate, saying he "truly helps McCain in his weakest area and that is the economy."

In a June blog, Carlson raised the prospect that criticism of the Pawlenty administration's Department of Transportation after the collapse of the Interstate 35W bridge could hurt his chances of being picked.

In an interview this week, Carlson said the discontent of some Hillary Rodham Clinton supporters about her losing the nomination could prompt McCain to pick a woman. "The biggest problem Obama has today is whether or not he can pull in the Hillary Clinton vote," Carlson said.

Carlson said Carly Fiorina, the former chief executive of Hewlett-Packard Co. and a top adviser to McCain, or Texas Sen. Kay Bailey Hutchison would be credible picks. Both have been named as possible McCain selections.

Others who have been considered on short lists for running mate include Connecticut Sen. Joseph Lieberman, an independent; Florida Gov. Charlie Crist and Louisiana Gov. Bobby Jindal.

Pat Doyle • 612-616-2026