One day after Scott Brown released a radio ad boasting of the "great experience" he had standing with President Barack Obama, Massachusetts Democratic Senate candidate Elizabeth Warren is airing a television ad statewide featuring Obama praising her.

"She's a janitor's daughter who has become one of the country's fiercest advocates for the middle class," says Obama. "She came up with an idea for a new, independent agency that would have one simple, overriding mission: standing up for consumers and middle-class families," he continues, referring to Warren's work in helping set up the Consumer Financial Protection Bureau. Richard Cordray, the former Ohio Attorney General, was eventually recess-appointed as the head of the bureau, over the protestations of Senate Republicans.

"The big banks tried to stop us. But that new agency is already working to cut the fine print, hold those banks accountable. We can take on the big guys and win," Warren says. The ad closes with an image of Obama and Warren sharing a laugh in the Oval Office.

Unusual for a Republican, Brown is touting his work with Obama, too. Speaking in a radio ad about a bill he introduced to give tax credits to businesses that hire veterans, he said, "Standing with President Obama on the day he signed it into law was another one of those great experiences." However, in a recent fundraising email sent to an out-of-state list, Brown wrote, "I know there are several other GOP campaigns to support, but this race is THE battleground for the United States Senate -- the only sure hedge to a potential second term for President Obama."

Obama is popular in Massachusetts, with a 58/35 favorability rating, according to a March Public Policy Polling survey.

The close Massachusetts Senate race is already shaping up to be the most expensive in the nation, with donations for the two candidates already rising above $30 million.

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