Consumer advocate and former White House official Elizabeth Warren will announce on Wednesday that she is running for the United States Senate seat currently held by Scott Brown (R-Mass.), a close source tells The Huffington Post. The announcement will not come as a surprise, as Warren has spent the last few weeks traveling across Massachusetts and speaking at several high-profile political events as part of a statewide listening tour. Still, her formal entrance into the race is likely to be cheered by progressives and national Democrats alike, as Warren is both beloved by the base and represents one of the party's best chances to unseat Brown.