Blocked by congressional Republicans from joining the Obama administration as a Wall Street watchdog, Elizabeth Warren will try to take her crusade against unfair lending practices to the U.S. Senate.

Warren announced today that she will challenge Sen. Scott Brown (R) for his Massachusetts seat in 2012, posting the above video to her new campaign website.

"Washington is rigged for big corporations that hire armies of lobbyists. A big company like G.E. pays nothing in taxes and we're asking college studs to take on even more debt to get an education? We're telling seniors they may have to learn to live on less? It isn't right, and it's the reason I'm running for the United States Senate," Warren said.

President Obama has given credit to Warren, a former Harvard professor who chaired Congress's board to oversee the TARP financial bailout, for dreaming up the Bureau of Consumer Financial Protection, an independent board within the Federal Reserve created under the financial-reform bill President Obama signed last summer. In September, Obama charged Warren with the task of setting up the bureau, appointing her as an adviser to Treasury Secretary Tim Geithner.

Warren seemed like the logical choice to head the board, but it became clear that Senate Republicans would refuse to confirm her for that job. Warren clashed with Republicans who summoned her to the Capitol to scrutinize the role of the new board, and at a contentious subcommittee hearing in May, Rep. Patrick McHenry (R-N.C.) notably accused her of lying about a purported agreement on the timing of her appearance.

In July, Obama passed over Warren and nominated Ohio Attorney General Richard Cordray instead. Speculation soon mounted that Warren would run for Senate.

Warren could face an uphill climb in her challenge to Brown: A WBUR poll this month showed Brown leading Warren 44-35 in a potential matchup. Working in Warren's favor are Massachusetts's history as a blue state, wide recognition among Democratic insiders, and her early entry into the race.

Video credit: Warren for MA