Elizabeth Warren, Harvard Law professor and architect of the Consumer Financial Protection Bureau, says she will challenge Sen. Scott Brown, R-Mass., in 2012.
Warren will announce her bid Wednesday with an online video while she was on a listening tour in Massachusetts, The Washington Post reported.
"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 Tuesday. "I want to change that. I will work my heart out to earn the trust of the people of Massachusetts."
The move was widely expected -- Warren already formed an exploratory committee and hired strategists.
Other Democratic contenders include CityYear founder Alan Khazei, activist Bob Massie and Newton Mayor Setti Warren.