Harvard professor and consumer advocate Elizabeth Warren will officially announce Wednesday morning that she will challenge Sen. Scott Brown (R-MA) in 2012 to reclaim the Senate seat for the Democrats, a senior Massachusetts Democratic Party official confirmed to Raw Story.

Warren’s candidacy has been the subject of speculation for more than a year. Last month, she conducted a listening tour around Massachusetts and formed an exploratory committee to test the waters and begin fundraising.

She will make a number of appearances across the state tomorrow to meet with voters, the official said, starting at an MBTA stop in Boston and working her way through the state’s different regions throughout the day. Like Tammy Baldwin, a Democratic candidate for one of Wisconsin’s Senate seats, she will announce her candidacy via a video posted to her campaign website.

A former economic adviser to President Barack Obama, Warren has taken her licks from Congress while giving anti-Wall Street testimony.

As a candidate, Warren will make sure Washington is working for working-class families, the aide said. On Wednesday’s tour, Warren will focus on meeting and greeting voters.

“The pressures on middle class families are worse than ever, but it is the big corporations that get their way in Washington,” Warren will say in Wednesday’s announcement video, according to a partial script obtained by The Boston Globe. “I want to change that. I will work my heart out to earn the trust of the people of Massachusetts.”

Warren’s entry into the race expands the field to seven Democrats against Brown, who is seeking his first full six-year term in the Senate. He won the seat in January 2010 in an upset over Massachusetts Attorney General Martha Coakley, to replace Sen. Ted Kennedy, who died of brain cancer in office in August 2009.