Senate Democrats may not have the constitutional authority to reject Illinois Gov. Rod Blagojevich's choice to fill President-elect Barack Obama's vacated Senate seat, election law experts told ABC News.
"Under these circumstances, anyone appointed by Gov. Blagojevich cannot be an effective representative of the people of Illinois and, as we have said, will not be seated by the Democratic Caucus," the Democratic leadership said in a statement.
Earlier this month, all 50 members of the Senate Democratic Caucus called on Blagojevich to step down and not to make an appointment to fill the seat. Illinois Secretary of State Jesse White also said today that he would refuse to certify Burris' selection.
But election law attorneys said that senators may not have the constitutional power to refuse to admit Burris into the Senate without some indication that his appointment was corrupt. It was unclear what would happen if Burris attempts to take his seat.
"There is very little that can be done to stop this, and I suspect it will go forward," said Ken Gross, the former associate general counsel of the Federal Election Commission.
Blagojevich was arrested earlier this month on a variety of corruption charges, including scheming to benefit from naming Obama's replacement in the Senate.
He has denied any wrongdoing and has said he would fight the charges and the attempts in the state legislature to impeach him. Burris said he has no connection to the charges against Blagojevich.
The Constitution gives the House of Representatives and the Senate the power to judge the "elections, returns and qualifications of its own members," and both houses of Congress have refused to seat members in the past.
In a 1969 decision, the Supreme Court held that Congress, when judging the qualifications of its members, is limited to the qualifications listed in the Constitution, such as age and citizenship. In that case, Powell vs. McCormack, the court held that the House of Representatives had inappropriately refused to seat Adam Clayton Powell.
A spokesman for Senate Majority Leader Harry Reid, Jim Manley, said Reid and the other senators were not making a judgment about Burris' qualifications, but about whether the appointment itself was tainted by fraud.
"This is like judging the integrity of an election, free from fraud or corruption," he said. "It's the process that led to the appointment, not the appointee's fitness."
Senate Historical Office associate historian Don Ritchie said there have been 24 people in the history of the United States who were not seated in the Senate, but there is no situation directly analogous to the one in Illinois right now in which a governor making an interim appointment is accused of seeking a bribe for that appointment.
"We don't know" what will happen, Ritchie said. "This has never happened before."
The Senate could block an appointment if it was made illegally, election lawyers said.
"The Senate has the power to judge whether an appointment may have been procured illegally somehow," said Eugene Volokh, a law professor at UCLA. "If it sounds like there's no reason to think that, then there is no constitutional basis for saying no.
"I don't see that they have a leg to stand on, unless they challenge the Supreme Court on Powell," he said.
The Senate does have some other options. The Democratic Caucus could refuse to admit Burris as a member. The Senate could also conduct an investigation into the circumstances of Burris' appointment or appoint a special prosecutor to satisfy itself that no corrupt activity took place.
"They could say we want to investigate the circumstances under which you were appointed and therefore will not seat you until we have conducted an investigation to our satisfaction or until Illinois changes the way it" makes appointments, said Jan Baran, the former general counsel to the Republican National Committee and to President George H.W. Bush's presidential campaign.
"A lot of things can happen," he said.