DENVER (AP) -- John McCain's campaign suggested Sunday that rival Barack Obama snubbed Hillary Rodham Clinton as his running mate because of her criticism during the battle for the Democratic nomination. Obama's campaign dismissed the claim as the candidate praised Joe Biden, the man he did choose.

Campaigning in the battleground state of Wisconsin, Obama said he was "absolutely convinced" fellow senator Biden was right for the job.

"He's got the passion to lift up middle-class Americans, he hasn't forgotten his working-class roots, he has the expertise that will make him a great counselor on international crises that might come up," Obama told reporters before boarding his plane in Eau Claire, Wis.

Earlier, speaking at a barbecue at a lakeside gun and rod park in Eau Claire, Obama said both he and Biden had humble roots and predicted the veteran lawmaker from Delaware would be "one of the greatest vice presidents in the history of the United States."

Meanwhile, a new McCain ad, the second since Obama made his vice presidential choice, challenged Obama's motives in passing over Clinton, his former top rival, and choosing Biden, who dropped out of the presidential contest after a poor showing in Iowa, the first contest. Chief Obama strategist David Axelrod insisted Biden was "a better fit."

House Speaker Nancy Pelosi, D-Calif., said Biden "has challenged the status quo. And he's even criticized Senator Obama, so it's a tribute to Senator Obama that he's not just choosing a yes man but a person who will speak what he believes."

Obama was also planned campaign stops in Iowa, Missouri and Montana before the nomination becomes his Thursday in Denver. He spoke in Eau Claire, a city of 65,000 about 85 miles east of St. Paul, Minn., site of the Republican convention the following week.

He said he was looking forward to hearing his wife Michelle speak on Monday night. "I'm still tooling around with my speech a little bit. It may not be as good as the other headliners the first three nights, but hopefully it will make clear the choices the American people are going to face in November," Obama said.

Also Sunday, the party's credentials committee voted to restore full voting rights to delegates from Michigan and Florida, despite their holding early primaries against party rules. With his nomination assured, Obama sought a show of unity to shore up support in those two important states.The states had initially been stripped of all their delegates for holding primaries before Feb. 5. The party's rules committee restored the delegates in May, but gave them only half votes.

Since Biden's selection on Saturday, the McCain campaign has come out with two campaign ads addressing the Democratic candidate's choice.

The latest, released by the campaign early Sunday, features clips of Clinton during the primary battle saying critical things about Obama, including, "Senator Obama's campaign has become increasingly negative."

A voiceover announcer says, "She won millions of votes but isn't on the ticket. Why? For speaking the truth."

Responding to the ad, Clinton spokeswoman Kathleen Strand said the New York senator's "support of Barack Obama is clear. She has said repeatedly that Barack Obama and she share a commitment to changing the direction of the country, getting us out of Iraq and expanding access to health care. John McCain doesn't. It's interesting how those remarks didn't make it into his ad."

Two potential swing-state governors - Virginia's Tim Kaine and Colorado's Bill Ritter - welcomed Biden's selection.

Kaine, who had been on Obama's short list for a running mate, said Obama and Biden were "a good team personality-wise. They complement each other well. I think you're going to see them really enjoying being out on the trail together."

Ritter said Obama and Biden together would help the ticket, particularly with independent voters in the West.

Meanwhile, reflecting Biden's new status, the Delaware delegation on Sunday got a seating upgrade on the convention floor, closer to the podium and close to the Illinois delegation.

Biden returned to Delaware after their first joint appearance Saturday in Springfield, Ill., where Obama had begun his campaign in February 2007.

Biden attended church near his home in Greenville, Del. He left the service without commenting to reporters. Obama attended morning services at First Lutheran Church in Eau Claire. McCain attended services at North Phoenix Baptist Church with his wife and daughter.

McCain, who had no public schedule Sunday, told CBS News that Biden was a "wise selection" who will be formidable. But the Arizona senator was critical of the Obama-Biden ticket on foreign policy, citing disagreements with Biden's decision to vote against the first Gulf War as well as his position that Iraq should be divided "into three different countries."

McCain, who has not announced his running mate, holds a 2-1 lead over Obama as more knowledgeable on world affairs and as better suited to be commander in chief, according to an ABC News-Washington Post poll released Sunday. The same poll, which gave Obama a slight 49 percent to 43 percent lead overall, found that three-fourths said the addition of Biden would make no difference in their vote, while the remainder were evenly split on whether it would make them more or less likely to vote for Obama.

Minnesota Gov. Tim Pawlenty, mentioned often as a potential No. 2 to McCain, said Sunday that Obama's choice of Biden had undermined one of the key messages of Obama's campaign, that he is an agent of change.

"Now you pick someone who is a consummate Washington insider, who was elected to the U.S. Senate when Barack Obama and I were 12 years old," Pawlenty said in a conference call with reporters. "Where's the change?" Pawlenty and Obama are both 47, Biden is 65, McCain is 71.

Meanwhile, Indiana Gov. Evan Bayh, who also had been on Obama's short list, said he called Biden on Saturday to congratulate him. "I think he is going to be great," he said.

As to any lingering hard feelings between the Obama and Clinton camps, Bayh, who had actively supported Clinton, said: "The convention will give us an opportunity to reach out to those people. Hillary is going to be 100 percent for him."

Anti-war activist Cindy Sheehan told about 200 demonstrators Sunday in Denver that not much has changed since her monthlong war protest outside President Bush's ranch in Crawford, Texas, in 2005.

The demonstrators gathered outside the Colorado state Capitol before marching through downtown Denver to the Pepsi Center, where the Democratic National Convention starts on Monday. It's the first of at least five protests planned this week by the group Recreate 68.

Axelrod spoke on ABC's "This Week," Kaine and Ritter appeared on "Fox News Sunday," Pelosi and Kennedy on NBC's "Meet the Press" and Bayh on CNN's "Late Edition."