Karl Rove, then-White House political director, and Republican national committeeman Robert Kjellander were among those mentioned in the alleged 2004 conversations, prosecutor Carrie E. Hamilton said.
Hamilton said the witness is former Illinois Finance Authority executive director Ali Ata, who on Tuesday pleaded guilty to tax fraud and lying to an FBI agent about Rezko's role in getting Ata his state job.
Rezko is on trial charged with scheming to use his clout with Gov. Rod Blagojevich's administration to launch a $7 million kickback scheme. Blagojevich has not been charged with any wrongdoing.
Hamilton told U.S. District Judge Amy J. St. Eve, who is presiding over Rezko's trial, that if Ata takes the stand he will tell the jury about conversations concerning an effort to derail the corruption investigation surrounding the Blagojevich administration by having U.S. Attorney Patrick J. Fitzgerald fired.
Hamilton said Ata "had conversations with Mr. Rezko about the fact that Mr. Kjellander was working with Karl Rove to have Mr. Fitzgerald removed."
"Mr. Rezko's explanation, according to Mr. Ata, is that Mr. Kjellander is working with Mr. Rove to have Mr. Fitzgerald removed so that someone else can come in to the U.S. attorney's office and individuals who have been cooperating in this investigation will be dealt with differently," Hamilton said.
She did not give further details and federal officials declined to say more.
Kjellander, reached by telephone, brushed the claim aside.
"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.
Robert Luskin, Rove's attorney, responded to a CBS News request for comment today by e-mail:
"Mr. Rove has known Mr. Kjellandar since college, but does not recall his ever suggesting that Mr. Fitzgerald be removed. Mr. Rove never spoke with anyone at the White House or elsewhere in an effort to secure Mr. Fitzgerald's removal.
"According to the published reports, the contact was allegedly made during 2004, when Mr. Fitzgerald was also serving as Special Counsel in the CIA leaks investigation. During that time, numerous people criticized Mr. Fitzgerald and the conduct of that investigation, but Mr. Rove never took any action that could conceivably be construed as an attempt to interfere with Mr. Fitzgerald's independence."
Prosecutors sought St. Eve's permission Wednesday to ask attorney Steven Loren, who has been on the witness stand for most of this week, about what sounded like talk of a similar plan.
St. Eve described it as a conversation between Loren and Springfield lobbyist-millionaire William Cellini "regarding attempts to conceal the conspiracy."
"Namely, his purported statements that they would have Mr. Fitzgerald removed," St. Eve said. But she ruled Loren could not be asked about such statements, saying they were outside the scope of the Rezko case.
Neither federal prosecutors nor defense attorneys would divulge any more particulars concerning the alleged Loren-Cellini conversation.
Loren was outside counsel to the Illinois Teachers Retirement System, the $40 billion state fund that pays the pensions of retired downstate and suburban school teachers.
Rezko is charged with scheming to pressure kickbacks out of money management firms wanting to invest TRS assets. He also is charged with scheming with attorney Stuart P. Levine to split a $1.5 million bribe from a contractor wanting state approval to construct a hospital in the McHenry County suburb of Crystal Lake.
Levine sat on the state boards that made both decisions.
Hamilton's description of Ata's statements marked the week's second bombshell linked to Rezko's trial.
The first came Tuesday when Ata said in a signed plea agreement with federal prosecutors that Blagojevich was on hand when Ata gave Rezko a $25,000 check for the Blagojevich campaign. Blagojevich immediately asked Rezko if he had discussed the possibility of a job on the state payroll for Ata, according the plea agreement.
Former U.S. Sen. Peter Fitzgerald, R-Ill., nominated Patrick Fitzgerald - no relation to the former senator - for U.S. attorney. He said at the time he wanted someone who would be independent in investigating Illinois' endemic corruption.
Since coming to Chicago, the New Yorker has sent former Gov. George Ryan and a number of other politicians to federal prison on corruption charges, while the Rezko case has provided numerous political black eyes for the incumbent Blagojevich.
Fitzgerald also was appointed the special prosecutor for Washington's CIA leak investigation in which I. Lewis "Scooter" Libby was convicted of perjury and obstruction of justice.
Luskin, who said he talked to Rove after his name came up in Rezko's trial Wednesday, said because Rove was a subject of that investigation, Rove "would have been especially sensitive to doing or saying anything that would appear to be interfering with Fitzgerald's independence."
The firings of U.S. attorneys around the country provoked a backlash on Capitol Hill last year, where lawmakers questioned whether the moves were politically motivated. That undermined the position of Alberto Gonzales, who wound up resigning as attorney general.