Washington ? Roland Burris failed to capture President-elect Barack Obama’s old Senate seat Tuesday in a wild piece of political theater, but the Democrats’ opposition cracked when a key chairwoman said seating him was simply the legal thing to do.

Democratic leaders, set to meet with Burris today, were searching for a way to defuse the dispute before it further overshadows the 111th Congress. Knowledgeable Senate officials of both parties widely predicted that the saga would end with Burris being seated. They spoke on condition of anonymity because they were not authorized to speak publicly.

Seating Burris seemed more likely late Tuesday, when Sen. Dianne Feinstein rejected the reasoning that all of the chamber’s Democrats, herself included, had cited in a letter last week — that corruption charges against Burris’ patron, Illinois Gov. Rod Blagojevich, tainted his appointment.

“Does the governor have the power, under law, to make the appointment? And the answer is yes,” said Feinstein, chairwoman of the Senate Rules Committee, which judges the credentials of senators.

Burris marched into the Capitol earlier Tuesday, declaring himself “the junior senator from the state of Illinois.” But Secretary of the Senate Nancy Erickson rejected his certification, as he knew she would, saying it lacked Illinois Secretary of State Jesse White’s signature and the state seal.

Late Tuesday, Feinstein urged the Senate to settle the matter.

“If you don’t seat Mr. Burris, it has ramifications for gubernatorial appointments all over America,” the California senator said. “Mr. Burris is a senior, experienced politician. He has been attorney general, he has been controller, and he is very well-respected. I am hopeful that this will be settled.”

A spokesman for Senate Majority Leader Harry Reid did not immediately respond to a request for comment.

Earlier, Reid had said, “Mr. Burris is not in possession of the necessary credentials from the state of Illinois.”

Burris, meanwhile, pivoted from his rejection at the Capitol to the Illinois Supreme Court, asking it to order White to certify his appointment.

Burris was expected to meet with Reid today.

It would be his second appearance at the Capitol in as many days. His first included an escort by Capitol police officers to Erickson’s third-floor office for what was described as a highly cordial, 21-minute meeting.

Burris, 71, then led a small mob of lawyers, consultants, police and reporters across the street in pouring rain, to a news conference which Burris aides said Reid had tacitly allowed.

Erickson, Burris reported, had advised him that “I would not be accepted, and I will not be seated, and I will not be permitted on the floor.”

The former Illinois attorney general said he was “not seeking to have any type of confrontation” over taking the seat. In addition to his court filing late in the day in Illinois, Burris said he was considering a federal lawsuit to force Senate Democrats to seat him.

It was a distraction for majority Democrats eager to project an image of progress with Obama on an economic stimulus package estimated to cost as much as $800 billion.