WAUKESHA, Wisc. -- With the 2012 Summer Olympics winding down, the 2012 presidential campaign geared up Sunday, with President Barack Obama and Republican presidential candidate Mitt Romney framing arguments and trading accusations that will likely set the tone and tenor of the upcoming political conventions and the fall campaign.

With new running mate Paul Ryan in tow, a reinvigorated Romney raced across North Carolina and Wisconsin Sunday, warning at each stop that an Obama second term would be economically devastating for America.

Paul Ryan made a celebratory return to his home state of Wisconsin on Sunday, heaping praise on the state's Republican governor, Scott Walker, for surviving a recall effort based on his push to cut collective bargaining rights for public workers.

“On June 5, courage was on the ballot in Wisconsin and courage won and courage won. We Wisconsinites, we saved Wisconsin that day,” said Ryan, chairman of the House Budget Committee and author of a budget plan that would cut taxes, federal spending and revamp Medicare. “And on Nov. 6, we Wisconsinites will help save America that day.”

Ryan told the crowd that Obama is leading the country on a path “toward a welfare state with a debt crisis.”

“Do we want to copy Europe?” No!” Ryan shouted.

Earlier in the day in North Carolina, Ryan told a crowd that packed into a furniture factory in High Point that “We have a clear choice of two futures.”

“Are we going to accept the status quo, a path of debt, a path of doubt and decline?” he asked. “We can turn this country around.”

Meanwhile, in Chicago, Obama formally welcomed Ryan to the campaign, invoking his name to a chorus of boos during a fundraiser at an arts center. The event was the second of five fundraisers in his home town Sunday.

"I know him, I welcome him to the race," Obama said, cutting the crowd’s booing off.

Obama called Ryan the "ideological leader of the Republicans in Congress."

Ryan is a "decent man, a family man" and an "articulate spokesman for Gov. Romney’s vision," Obama said.

"But it’s a vision I fundamentally disagree with," he added. "The question in this election is which way do we go? Do we go forward toward a vision of American in which prosperity is shared... or do we go backward, toward the same policies that got us into this mess in the first place. I believe we have to go forward."

David Axelrod, Obama’s senior advisor, was even less genteel. He called Ryan a “right-wing ideologue” on CNN’s “State of the Union.”

Ryan may have been panned in Chicago but his presence on Romney’s ticket was praised in North Carolina and Wisconsin, key states in November’s election.

“I liked Romney, when he picked Ryan I really liked him,” John Nowak of Charlotte said outside Romney’s appearance in Mooresville, N.C.

The Republican team was greeted by a large-crowd in Waukesha, a heavily Republican town about 20 miles outside Milwaukee. Traffic was snarled outside the expo center where the candidate appeared two hours before the event. The state’s governor and the Republican Party’s standard bearer took second-billing to Ryan, the first person from Wisconsin to be on a major presidential ticket.

"I love Paul Ryan, because he’s a good conservative candidate who actually has a plan to fix things. He put pen to paper instead of just blah blah blah," said Jill Radi of Waukesha.