WASHINGTON (AP) -- Senate appointee Roland Burris will be sworn into office Thursday, his office said, closing a painful and protracted certification process ensnared in the federal corruption investigation of Illinois Gov. Rod Blagojevich.

Senate Democrats have reversed course, grudgingly accepting the former Illinois attorney general into their exclusive club as the person who will replace the Senate seat vacated by President-elect Barack Obama.

"I really never doubted that I would be seated," Burris said in a nationally broadcast television interview Tuesday. "It was just a matter of going through the process and making sure that the Senate rules were abided by," he said.

Asked about any role that Obama might have played in softening the opposition to his seating by Senate Democratic leaders Harry Reid and Dick Durbin, Burris said, "I have no knowledge of what the president-elect did."

Reid, D-Nev., and Durbin, D-Ill., made the announcement of acceptance in a joint statement Monday, saying Burris "is now the senator-designate from Illinois and, as such, will be accorded all the rights and privileges of a senator-elect."

In a statement issued late Tuesday, Burris' office said Vice President Dick Cheney would administer the oath to Burris on the Senate floor Thursday afternoon.

Burris called himself honored and humbled to be the state's newest senator. "I'm thankful for the opportunity to serve," he said at a news conference Monday in Chicago. "I recognize that my appointment triggered a challenging time for many."

The development prevented the impasse that has plagued Democrats from dragging on into Obama's inauguration festivities, and it capped a gradual retreat by the Senate's top Democrats.

Durbin, who joked at a Tuesday morning news conference on Capitol Hill that he was for the moment both the junior and the senior senator from his state, said Burris would soon be out from under the cloud that has hung over his appointment.

"Roland Burris has a great reputation in Illinois as an elected official, over time, statewide, and I believe he will bring that record and his skills to this office and soon become his own man," Durbin said.

Of the flap surrounding Burris' naming, Durbin said, "Now we're beyond it. I think he's going to be a very good United States senator, and I look forward to serving with him."

The top Democrats had initially tried to dissuade Blagojevich, who faces criminal charges, from making an appointment and suggested that his pick would not be seated. Last week, Burris' credentials were rejected in a circus-like atmosphere that tarnished the opening day festivities of the new Congress.

But Reid and Durbin said they anticipated that Burris would be seated this week, barring objections from Republicans. They made the announcement after Burris lawyers delivered to the Capitol documents certifying his appointment to Obama's seat, and the secretary of the Senate determined that the paperwork met Senate requirements.

In an interview on MSNBC, Burris reiterated that he had made no deal with Reid not to run for a full Senate term in 2010 in exchange for being allowed to take his seat in the chamber now.

He said he would work in the Senate to win approval of Obama's economic stimulus package in the hope that the measure would help the economy and create jobs. "I would like to see thousands of jobs created in Illinois and millions of jobs created in the country," Burris said.

Reid and Durbin said they were satisfied both with the documents and with Burris' testimony before the Illinois House impeachment panel that he did nothing wrong.

Even though Burris does not stand accused of wrongdoing, Senate Democrats rejected Burris last week, only to quickly backpedal after Obama himself privately weighed in and senators fretted that the situation was diverting their focus at a critical time.

Asked on NBC's "Today" show if his service in the Senate could still carry a taint because of Blagojevich's legal problems, Burris said he didn't think so.

"They need to look at my record ... what I have done over the years as a citizen of our state," Burris said.

He also declined to join in calls for Blagojevich to resign, saying "my position is that you're innocent in this legal system until you're proven guilty."

He said any demand that he would make for Blagojevich to step down "would have no effect."