US Senate leaders have refused to allow the man chosen by Illinois's scandal-tainted governor to replace US President-elect Barack Obama to be sworn in at the start of a new Senate session.
‘I presented my credentials to the secretary of the senate, and advised that my credentials were not in order,’ Roland Burris said, after arriving at the Capitol building surrounded by reporters.
Mr Burris, the former Illinois Attorney General, was picked to fill Mr Obama's vacant Senate seat by Illinois governor Rod Blagojevich last week.
He said he was not seeking a confrontation on the first day of the new Senate and would now consult his lawyers.
Gov Blagojevich is under investigation amid allegations he had sought to sell the empty Senate seat to the highest bidder.
However until he resigns or is removed from office, he still holds the sole power to pick Mr Obama's replacement.
Illinois political leaders hope to begin impeachment hearings soon, but they are not expected to begin before Mr Obama's inauguration ceremony on 20 January.
That technically leaves Illinois with just one representative in the US Senate.
