WASHINGTON (February 4, 2010)--Scott Brown was sworn in as a U.S. senator Thursday afternoon.

Vice President Joe Biden wore in the Massachusetts Republican Thursday afternoon in a Capitol Hill Ceremony.

Brown fills the seat of the late Edward Kennedy, who died of brain cancer in August.

The little-known former Massachusetts state senator rocked the nation with his upset victory last month over a favored Democrat and put this year's midterm elections in play for a possible GOP takeover of Congress.

Brown's arrival ends the Democrats' Senate filibuster-proof supermajority and gives the GOP 41 votes they can use to block President Barack Obama's agenda.

Brown has promised to be an independent voice.

He told Republican leaders recently they won't always be able to count on his vote.