Harvard Law Professor Elizabeth Warren is making it official — she’s running against Sen. Scott Brown (R-Mass.) in 2012.

The former Obama admistration official will announce her bid Wednesday with an online video as she continues her tour of Massachusetts.

“The pressures on middle class families are worse than ever, but it is the big corporations that get their way in Washington,” Warren said in a statement. “I want to change that. I will work my heart out to earn the trust of the people of Massachusetts.”

Warren appears before the Senate Finance Committee with TARP Special Inspector General Neil Barofsky and acting U.S. Comptroller General Gene Dodaro to testify about TARP oversight. (Chip Somodevilla/GETTY IMAGES)

While Warren joins a crowded primary field, she is expected to vault to frontrunner status upon launch. A recent WBUR poll showed her nine points behind Brown — closer than any other Democratic candidate. She is also better known than any of the other would-be challengers.

Warren helped create the Consumer Financial Protection Bureau, winning the support of liberals nationwide and the ire of Republicans in Congress.

Other Democratic contenders include CityYear founder Alan Khazei, activist Bob Massie and Newton Mayor Setti Warren. Mayor Warren is touting his win in a Methuen straw poll this weekend.

Last year, Brown won a special election to the seat formerly held by the late Sen. Edward Kennedy (D) in a surprise upset. He is hoping to win his first full six-year term next fall. Despite Massachusetts’ Democratic nature, he is enduringly popular in the state.

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