CHICAGO - Brushing aside charges that he tried to sell Illinois' vacant U.S. Senate seat, Gov. Rod R. Blagojevich appointed former Illinois Attorney General Roland Burris to the post yesterday in defiance of Senate leaders who said they would not admit anyone he selected.

It was an abrupt about-face for Blagojevich, who had said after his Dec. 9 arrest on corruption charges that he favored a special election to find a successor to President-elect Barack Obama. But he said he acted after the Democratic-controlled General Assembly declined to approve legislation for a special election.

"Please don't allow the allegations against me to taint this good and honest man," Blagojevich said as he introduced Burris at a news conference.

Burris, 71, was the first African American elected to statewide office in Illinois. Obama, in a statement, called him "a good man and a fine public servant," but said he sided with Senate Democrats who have stated "that they cannot accept an appointment made by a governor who is accused of selling this very Senate seat."

"I agree with their decision, and it is extremely disappointing that Governor Blagojevich has chosen to ignore it," Obama said. He said the best resolution would be for the governor to resign "and allow a lawful and appropriate process of succession to take place."

Blagojevich's move seemed designed to trump fellow Democrats who control the U.S. Senate and have unanimously warned him against making the appointment because of the criminal charges he faces.

His choice of Burris presents a dilemma to senators of saying no to an African American replacement for Obama, who was the nation's only black senator.

That point was driven home at Blagojevich's news conference by Rep. Bobby Rush (D., Ill.), who said it was a matter of national importance.

"Let me just remind you that there presently is no African American in the Senate. . . . This is just not a state-of-Illinois matter," he said.

"I would ask you to not hang or lynch the appointee as you try to castigate the appointer," Rush said. "Roland Burris is worthy."

The governor's announcement came less than an hour after the Senate Democratic leadership issued a statement reiterating that the Senate would not seat anyone Blagojevich chose. Among the signatories was Illinois' senior senator, Richard J. Durbin, who had repeatedly urged Blagojevich not to name a Senate replacement for Obama.

"This is not about Mr. Burris; it is about the integrity of a governor accused of attempting to sell" the seat, the statement read. "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 decision was made during a 10-minute conference call involving Durbin, Majority Leader Harry Reid of Nevada, and Sen. Robert Menendez of New Jersey, as well as representatives of Sen. Charles E. Schumer of New York. There was little discussion and no dissent in reaching the position, a Senate aide said.

Reid had previously warned Blagojevich, after his arrest, that Senate Democrats would not seat any appointee he named; a letter to that effect was signed by all sitting Democratic senators.

Illinois Secretary of State Jesse White, a Democrat who is one of the state's most popular vote-getters, said he would not certify Burris. But White aides acknowledged that the lack of a signature on the certification form was symbolic.

Lt. Gov. Pat Quinn said Blagojevich's move was an "insult to the people of Illinois."

"We believe in clean government, and Rod Blagojevich has unclean hands," Quinn said.

Democratic State Rep. Monique Davis of Chicago, a member of the legislative committee considering impeaching Blagojevich, said his appointment of Burris would have no bearing on its decision.

"Anybody that wants to put the race card in there, they're playing with the wrong group of people," Davis said. "We're not going to operate that way. . . . We're not going to say, 'Oh, look what a good thing he's done.' We're not going to do it."

Burris, in accepting the appointment, said it was "incomprehensible that the people of the great state of Illinois will enter the 111th Congress shorthanded. We need leadership in Washington."

Burris was Illinois' comptroller from 1979 to 1991 and its attorney general from 1991 to 1995. He was vice chairman of the Democratic National Committee from 1985 to 1989. He lost campaigns for the Democratic gubernatorial nomination in 1994, 1998 and 2002 - the last time to Blagojevich.

He has given more than $20,000 to Blagojevich's campaign fund on his own and through his consulting and law firms, state records show.

Shortly after Obama's Nov. 4 victory, Burris made his interest in the appointment known but was never seriously considered, according to Blagojevich insiders. In the days after Blagojevich's arrest - and despite questions over the taint of a Senate appointment by him - Burris stepped up his efforts to win the governor's support.

Burris said that he spoke about the matter with Blagojevich on Sunday night.

"I was asked if he would appoint me, would I accept, and the answer is yes," said Burris. He said he had no comment on the governor's legal situation.

The governor's announcement came three weeks after his arrest on political-corruption charges. Federal authorities, citing wiretap recordings, allege that Blagojevich sought a cabinet post, an ambassadorship, or a high-paying job from the Obama administration in exchange for naming a candidate favored by Obama.

This article includes information from the Associated Press.