U.S. senators opposed to Illinois Gov. Rod Blagojevich's defiant appointment to Barack Obama's vacant seat could try to block the move by using a time-honored tradition -- stall tactics. 

Roland Burris, the former Illinois attorney general appointed to the seat by the governor despite the corruption charges against him, plans to head to Washington next week when new senators are sworn in. 

Democrats have threatened to refuse him entry, but Burris' supporters and some legal experts say they are on shaky constitutional ground since Burris is technically eligible and Blagojevich is within his right to make the appointment. Burris has already taken the Illinois secretary of state to court in a bid to force him to certify the appointment, as required by Senate rules. 

So Senate Democratic officials are looking at the possibility of making a motion to refer Burris' credentials to the Rules and Administration Committee for a review. That could take months, by which time Blagojevich may no longer be governor, officials said. Burris would not be granted a paycheck or office space or floor privileges in the meantime, the officials said. 

Senators could simply attempt to run out the clock, as an Illinois House panel proceeds with its impeachment inquiry and U.S. Attorney Patrick Fitzgerald seeks an indictment against the governor. Lt. Gov. Pat Quinn is waiting in the wings to take over and potentially make an appointment of his own. 

"What Harry Reid can do is delay this for many, many months," said Democratic strategist Julian Epstein. "By that time, Blagojevich should be out of office, and then hopefully we can have a proper appointment." 

Democrats are talking about the option of senators choosing between Burris and a rival appointee from Quinn, should Blagojevich be forced out of office. 

"I hope we're able to move forward with impeachment as quickly as possible," Illinois state Rep. Susana Mendoza, a Democrat, told FOX News. "I think the U.S. Senate is hoping that we give them more options, maybe choosing between two different appointed candidates once Lt. Gov. Pat Quinn becomes governor. That's a possibility." 

Robert Walker, former counsel to the Senate ethics committee, said it seems likely the Senate would refer the matter to committee while impeachment proceedings transpire. He said such an inquiry would be legitimate but guessed "there may be some elements of a stall to it." 

The Senate has considered competing candidates before. The chamber, for instance, seated Democrat Mary Landrieu following her victory in the 1996 Louisiana Senate race, even though Republican Woody Jenkins alleged voter fraud and called for the seat to be declared vacant and a special election to be ordered. 

In 1975, the Senate did declare a seat from New Hampshire vacant after considering challenges from Democrat John Durkin and Republican Louis Wyman, who were locked in what was considered the closest election in Senate history. Durkin won in a special election. 

If the current Senate were to eventually choose between two possible appointees to Obama's seat, Walker said lawmakers might have to justify their choice through the rules committee process. But he told FOXNews.com that option may be more viable than simply denying Burris entry without an alternative candidate. 

Senate Democrats are claiming Burris would enter the chamber "plagued by questions of impropriety" because of the circumstances of the appointment. Blagojevich was arrested last month on charges of trying to sell the same seat to which he appointed Burris. 

Senate Majority Leader Harry Reid says the senators are entitled to judge the appointment regardless because Article 1 Section 5 of the U.S. Constitution states each chamber "shall be the judge of the elections, returns and qualifications of its own members." 

But if Burris forces the certification of Illinois Secretary of State Jesse White, experts and officials say the U.S. Senate would invite a lawsuit by refusing Burris entry solely over objections to Blagojevich. 

Burris and Blagojevich could potentially cite the decades-old case of Adam Clayton Powell Jr. in defending their legitimacy. Powell sued after the House refused to seat him in 1967 over corruption allegations. Because Powell was qualified and won election, the Supreme Court overruled the House and Powell returned to the chamber. 

Reid's office says the case is not relevant, but other legal experts aren't so sure. 

"I don't know why that wouldn't apply," said defense attorney Gerald Lefcourt, calling the Powell case a clear precedent for the matter before the Senate. 

Even though the Senate has refused entry before -- Illinois Senator-elect Frank Smith was barred over ethical questions in 1928-- a recent report from the Congressional Research Service stated that the Powell case renders past decisions of "suspect relevance." 

The report said it is now "clearly understood" that the Senate can only vote to exclude a member if there are questions about whether the candidate meets constitutional qualifications (age, citizenship and residence) or has been "duly elected." 

"The Senate doesn't really have a legitimate reason not to seat Burris. He's qualified to come to the Senate. It'll be interesting to see what Harry Reid does when he shows up," said Michael Steele, GOPAC chairman and former Republican lieutenant governor of Maryland. "Blagojevich, in my view right now, has the upper hand in this thing." 

Meanwhile, Burris is defending his right to the seat. He said friends -- he would not identify them -- are studying his legal options. He insisted that being named to the Senate by Blagojevich does not mean he is tainted by the governor's scandal. 

Burris is predicting he will be the next senator from Illinois, but said Wednesday that he will not create a scene if he is turned away next week. 

Some Democrats still want Burris to take the initiative and cut short what could be a prolonged and distracting intra-party fight at the start of the Obama administration. 

"This could all end right now if Mr. Burris does the right thing," Mendoza said. "The only way he can do that is by stepping down." 

Though Democrats have mostly steered clear of criticizing Burris' credentials, Mendoza said his acceptance of the appointment "puts his integrity in question." 

"We're dealing with two complete narcissists here," she said. 

FOXNews.com's Judson Berger and The Associated Press contributed to this report.