Roland Burris on Monday won his bid to fill the seat in the U.S. Senate vacated by President-elect Barack Obama, overcoming objections from Democratic leaders who now stand ready to enjoy their biggest majority since 1981.

Barring unanticipated roadblocks from Senate Republicans, Burris, appointed to the seat by embattled Illinois Gov. Rod Blagojevich in December, could be sworn in within days, giving Democrats 58 of the Senate’s 100 seats.

The decision by Senate officials to swear in Burris was a major about-face by the Democratic leadership, which initially vowed that the appointment would not stand because Blagojevich has been charged with having earlier tried to sell the seat.