Illinois Senate appointee Roland Burris left Monday for a high-stakes showdown in Washington with Democratic leaders who continue to say he won't be seated.

Burris Heads To D.C. To Claim Senate Seat

At the airport, Burris told reporters that he is going to Washington to be seated in the Senate.

"I am the junior senator of Illinois according to every law book in the nation," Burris said.

Paperwork naming Burris to the seat was received by the U.S. Senate secretary Monday morning, but was not formally accepted, according to a spokesman for embattled Democratic Gov. Rod Blagojevich.

Blagojevich appointed Burris last week despite Democratic leaders' pledge not to seat anyone named by the governor facing federal corruption charges.

Dozens of black leaders and ministers organized by U.S. Rep. Bobby Rush gave Burris a rousing send-off Sunday at New Covenant Church on Chicago's South Side.

Burris took the stage to a crescendo of drums, organ music and applause as hundreds of supporters cheered his appointment.

Burris told them the appointment is legal and he doesn't know what "all the confusion is about."

Before the service, Rush and about 60 ministers condemned Senate Democratic leaders for rejecting Burris.

Rush, a Chicago Democrat, called the Senate "the last bastion of plantation politics."

Earlier in the day, Senate Majority Leader Harry Reid told a political talk show host that the chances of Burris being sworn in as President-elect Barack Obama's replacement are slim.

Reid said there would be "a cloud" over any Blagojevich appointee.

The governor, who's facing the threat of impeachment, is accused of earlier attempts to sell the seat.