"I'm from Chicago," Barack Obama used to tell voters wondering whether he was tough enough to win the presidency, drawing laughs for referring to rough-and-tumble - and often corrupt - politics in his hometown.
But the arrest of Illinois Gov. Rod R. Blagojevich on charges of trying to sell Mr. Obama's vacant Senate seat to the highest bidder is probably not what the president-elect had in mind.
Authorities stressed that Mr. Obama was not involved in the far-flung corruption probe, but a 76-page FBI affidavit mentions a top Obama adviser who will be a senior White House staffer, a prominent labor union that worked for his candidacy, convicted felon and former Obama fundraiser Tony Rezko, and Washington-based consultants.
Within hours, lawmakers from both parties were calling for Mr. Blagojevich's resignation and Republicans were trying to exploit the scandal by demanding that Mr. Obama offer more details about his relationship with the disgraced governor.
"We're at an all-time low in our state," said Rep. Bobby L. Rush, Illinois Democrat.
The Illinois legislature was expected to call for a special election to fill the vacant Senate seat, a move that drew praise from some but which Mr. Rush said would put black candidates at a disadvantage.
Rep. Eric Cantor of Virginia, the No. 2 Republican in the House as minority whip, called on Mr. Obama to offer a clear statement right away about the investigation.
"The serious nature of the crimes listed by federal prosecutors raises questions about the interaction with Governor Blagojevich, President-elect Obama and other high-ranking officials who will be working for the future president," he said. "Simply put, I ask President-elect Obama to publicly explain tomorrow exactly what steps he is going to take to ensure that the forthcoming investigation is independent, fair, open and honest. Those planning to work for President-elect Obama should be as forthcoming."
Democrats who had been reveling in their presidential victory were suffering political heartburn Tuesday as the federal corruption charges detailed expletive-laden conversations and Mr. Blagojevich cursing the president-elect.
"The conduct would make Lincoln roll over in his grave," U.S. Attorney Patrick J. Fitzgerald told reporters Tuesday, referring to the last president to hail from Illinois.
"If Illinois isn't the most corrupt state in the United States, it's a strong competitor," FBI chief Robert Grant said during the press conference.
Mr. Blagojevich's predecessor George Ryan is serving jail time for racketeering and fraud. The current governor is on track to be the fifth Illinois chief executive to be indicted or convicted since 1929.
Mr. Obama told reporters he had no knowledge of the goings-on in the governor's office, and authorities said the person they identified as Senate Candidate 1, thought to be transition co-chairwoman Valerie Jarrett, had done nothing wrong.
The president-elect said he was "saddened and sobered" by the news but that it was not appropriate for him to comment on an ongoing investigation.
"I had no contact with the governor or his office and so we were not, I was not aware of what was happening," he told reporters in his only public remarks about the matter.
But Obama top adviser David Axelrod last month told Fox News that Mr. Obama had spoken with Mr. Blagojevich. Mr. Axelrod released a statement Tuesday saying he was incorrect, adding that "they did not then or at any time discuss" the Senate vacancy.
Appearing on NBC's "Meet the Press" on Sunday, Mr. Obama joked about the jockeying for his vacant seat when asked about Sen. Hillary Rodham Clinton's seat in New York.
"The last thing I want to do is get involved in New York politics. I've got enough trouble in terms of Illinois politics," he said.
The Service Employees International Union, which pushed Miss Jarrett for the vacant seat, would not talk about the union's involvement but insisted that the group was not involved in any wrongdoing.
The affidavit and taped phone conversations in Mr. Blagojevich's office reveal that Miss Jarrett was Mr. Obama's top choice to be his successor, but the governor said "unless I get something real good for" naming her, he may appoint himself for the vacancy.
On Nov. 7, the governor, his chief of staff and a D.C. consultant held a call to talk about "a three-way deal for the Senate appointment involving ... Change to Win ... affiliated with the SEIU," according to the charges.
"Advisor B said they should leverage the president-elect's desire to have Senate Candidate 1 appointed to the Senate seat in order to get a head position with Change to Win and a salary," the affidavit reads. "Later in the phone call [Mr.] Blagojevich stated that absent getting something back, [he] will not pick Senate Candidate 1."
During a two-hour phone call Nov. 10 with a larger group, the governor discussed how he would "obtain a position as the national director of Change to Win" in a deal where he named "Senate Candidate 1" to the seat.
The affidavit states that "Advisor B" told the governor the Change to Win idea was good because "from the president-elect's perspective, there would be fewer 'fingerprints' ... [and] 'you won't have stories in four years that they bought you off.'"
The charges detail an SEIU official, thought to be the group's leader Andy Stern, meeting as "an emissary" for "Senate Candidate 1."
On Nov. 12, Mr. Blagojevich spoke to the official and told him that he was interested in heading a 501(c)4 organization and "the union official agreed to 'put that flag up and see where it goes,'" according to the charges.
That day, Miss Jarrett took herself out of the running for the seat and by the end of the week she had been named to be Mr. Obama's public liaison, senior adviser and assistant to the president for intergovernmental relations.
Miss Jarrett is a close Obama family friend who worked for the campaign and has traveled with the Democrat many times.
Last week she was driven in the president-elect's motorcade from the Chicago transition office to her mother's home in Mr. Obama's neighborhood.
SEIU spokeswoman Ramona Oliver released a brief statement saying the union would not share information with the press but, "We have no reason to believe that SEIU or any SEIU official was involved in any wrongdoing."
Change to Win spokesman Greg Denier was more emphatic.
"No one connected with Change to Win ever considered, discussed or promised any position at Change to Win to Governor Blagojevich, his staff or his advisers," he said, adding that the affidavit shows the group was being talked about but is not mentioned as participating in the scandal.
"The first time Change to Win learned of any of the matters raised in the criminal complaint was with today's public release of the affidavit," he said.
Mr. Fitzgerald told reporters, "The complaint makes no allegations about the president-elect whatsoever," and said the "scheme" Mr. Blagojevich envisioned "did not come to fruition."
Also mentioned in the affidavit is "Senate Candidate 5," a man who has done fundraising for the governor. On Dec. 4, the governor said he was giving the candidate "greater consideration" because the candidate would raise money for him and later said the candidate might give him something "tangible up front."
Republican National Committee Chairman Mike Duncan said Mr. Obama's comments were "insufficient at best" because the Democrat has supported and advised his home-state governor.
The RNC also sent out a release detailing Mr. Obama's thin relationship with the governor - they each endorsed the other, but traveled in different Democratic circles. Mr. Blagojevich did not advise Mr. Obama during the campaign and they were not friends.
Federal prosecutors were investigating the governor for months, a probe that increased following the conviction of Rezko in June on corruption charges.
The spring trial for Rezko, who fundraised for both Mr. Blagojevich and Mr. Obama, revealed that the governor talked about giving a contributor a job in exchange for donations.
Chicago's political scandals date back more than a century, when leaders of the City Council took bribes.
Rep. Danny K. Davis was once considered a contender for the Obama seat but Tuesday took himself out of the running, telling ABC News that he did not want a "tainted" appointment.
He said in a statement that it is tough to quantify the harm done to the public trust in government.
"In a state still rocked by the convictions of Governors George Ryan, Dan Walker and Otto Kerner, this document suggests wrongdoing on a scale never before seen," he said of the affidavit.
Mr. Rush said Tuesday that he would fight to block a special election. He said the process would take too long and would leave minority candidates at a disadvantage in the race to replace the Senate's only black member.
The eight-term South Side Chicago congressman, who turned back Mr. Obama's challenge to his seat in the 2000 Democratic primary, did not say how the vacant seat should be filled.
The state would be facing primaries and a new general election for the seat that might not take place until April or May, he said, adding: "We can't wait that long."
• S.A. Miller and David R. Sands contributed to this report.