(CNN) - Milwaukee Mayor Tom Barrett, a Democrat, joined in on the attacks Monday against GOP presidential hopeful Mitt Romney, carrying his party's line that the former Massachusetts governor is a flip-flopper.
His remarks come on the heels of a new Democratic National Committee commercial airing in several battleground states - including Wisconsin - that pits Romney's own words against him on multiple issues.
"Trying to figure out where Mitt Romney is on a given issue can be exhausting," Barrett said at the Democratic Party of Milwaukee County Headquarters. "It must be just as tiring for him because when you take every position under the sun, it can't be easy to remember what you're supposed to believe today."
Barrett was one of several Democratic elected officials in likely swing states who stumped for the DNC’s campaign on Monday.
Former Ohio Gov. Ted Strickland appeared at the state party headquarters to promote the latest ad.
Florida Rep. Debbie Wasserman Schultz and Maryland Lt. Gov. Anthony Brown took part in a conference call to spread the message.
A host of other state representatives and Democratic Party chairs also acted as surrogates on Monday.
Saying the most interesting debates this election cycle have been the "debates between Romney and Romney," the Milwaukee mayor listed off a number of examples that he said shows the presidential candidate changing his tune over the years.
In his speech, Barrett referenced the ad, which features Romney giving different answers on issues, such as abortion rights and health care.
The video, however, leaves out Romney’s full answers to the questions.
For example, on President Obama's sweeping health care reform - which Romney has repeatedly said should be repealed - the ad shows him saying: "We put together an exchange, and the president's copying that idea. I'm glad to hear that."
That quote, from a 2009 interview with CBS News, fails to capture Romney's full sentiment. In the same answer, Romney later chided Obama for taking the wrong direction on health care.
"You don't set up a government insurance plan because it's going to end up costing billions of dollars in subsidy. It's the wrong way to go," Romney said.
While Barrett said he believes it's understandable for politicians to take evolving positions over time, he said Romney was an exception and faulted him for changing his message on "basic issues."
"I think his words are the most damaging weapon against him," he said.
Asked if he thinks Romney will be the Republican nominee, Barrett said it was too early to make that prediction.
Romney’s team responded to the attacks throughout the day, hitting back through their own surrogates who said in a series of phone conferences that the DNC’s campaign only showed Democratic fears of Romney potentially posing a threat to Obama if he becomes the nominee.
"It's a reflection of Mitt's strength and a reflection of how worried they are about the prospect of facing him in a general election," said former 2012 presidential candidate Tim Pawlenty.
Virginia Lieutenant Gov. Bill Bolling, who chairs Romney’s campaign in the state, told reporters on the phone that he was “ecstatic” about the Democrats’ new commercial, as he believes it means that Romney is gaining momentum in the race.
“I hope they keep spending their money in Virginia. I hope they keep running these kinds of ads,” Bolling said. “I'm confident that Gov. Romney is going to be the nominee of the Republican Party."
- CNN's Kevin Liptak and Gabriella Schwarz contributed to this report.