As one of the nation's toughest prosecutors on corruption, Patrick J. Fitzgerald is viewed with icy suspicion at best among Chicago's cigar-chomping, patronage-loving, backroom politicians.

But prosecutors dropped a bombshell Wednesday at political fundraiser Antoin "Tony" Rezko's corruption trial, suggesting some of Fitzgerald's foes may have gone beyond mere grumbling about his hard-nosed approach.

They say a government witness claims Rezko discussed efforts among top Republicans, including former White House political director Karl Rove and GOP national committeeman Robert Kjellander, to have Fitzgerald fired to derail a corruption probe.

That witness is Ali Ata, whom prosecutors want to be allowed to testify about his alleged 2004 conversations with Rezko. Ata, a former executive director of the Illinois Finance Authority, pleaded guilty Tuesday to tax fraud and lying to an FBI agent about Rezko's role in getting Ata his state job.

"He had conversations with Mr. Rezko about the fact that Mr. Kjellander was working with Karl Rove to have Mr. Fitzgerald removed," Assistant U.S. Attorney Carrie Hamilton told U.S. District Judge Amy J. St. Eve on Wednesday.

Hamilton didn't say much more, but she did make it clear that the idea was allegedly to derail, or at least slow, the federal government's probe of influence peddling involving Democratic Gov. Rod Blagojevich's administration.

At the time of the purported talks, Fitzgerald already had been appointed a special prosecutor for Washington's CIA leak investigation, in which I. Lewis "Scooter" Libby was later convicted of perjury and obstruction of justice.

Rezko is charged with scheming to use his clout with Blagojevich's administration to launch a $7 million kickback scheme. Rezko, who also raised funds for Sen. Barack Obama, says he had nothing to do with the schemes. Neither Obama nor Blagojevich are charged with any wrongdoing.

Kjellander, reached by telephone, brushed aside Hamilton's claim.

"I never have discussed with Karl Rove or any other person on the White House staff the proposition that U.S. Attorney Patrick Fitzgerald should or could be removed from his office," he said.

Rove's Washington attorney, Robert Luskin, said Rove and Kjellander have been friends since college, but Rove does not remember Kjellander ever talking to him about Fitzgerald.

"He does not recall Kjellander speaking to him about Pat Fitzgerald and is certain he never spoke to anyone at the White House about removing Fitzgerald," Luskin said Wednesday. Rove has never been contacted by the U.S. attorney's office about the alleged conversations, he said.

Luskin said Rove, being the subject of the CIA leak investigation, "would have been especially sensitive to doing or saying anything that would appear to be interfering with Fitzgerald's independence."

Since coming to Chicago, Fitzgerald has sent former Gov. George Ryan and other politicians to prison on corruption charges, and the Rezko case has provided political black eyes for Blagojevich.

Last year, the firings of U.S. attorneys around the country provoked a backlash on Capitol Hill, where lawmakers questioned whether the moves were politically motivated. Alberto Gonzales later resigned as attorney general.

Copyright 2008 Associated Press