March 18 (Bloomberg) -- A former top aide to Attorney General Alberto Gonzales who is challenging his ex-boss's description of the circumstances surrounding the firings of eight federal prosecutors is likely to testify to Congress, Democratic Senator Charles Schumer said.

Kyle Sampson, who was Gonzales's chief of staff, has been negotiating through his lawyer about an appearance before the Senate Judiciary Committee, said Schumer, a member of the panel and one of the lawmakers calling for Gonzales to step down over the handling of the dismissals last year.

``Last night we heard from his attorney that Kyle Sampson really wants to come forward,'' Schumer, of New York, said on NBC's ``Meet the Press'' program. ``He has said he wants to do that, and I think that's a very likely possibility.''

Sampson resigned March 13 amid revelations that White House officials were involved in the decisions to fire the prosecutors, some of whom were involved in investigating political corruption and election fraud cases. Gonzales said last week that Sampson failed to share information with other Justice Department officials about his dealings with the White House regarding the dismissals.

Sampson's attorney, Bradford Berenson, declined to comment.

Discussions `Well-Known'

In a March 16 statement, Berenson said Sampson didn't mislead anyone or withhold information about the replacement of the prosecutors. He resigned because ``he felt he had let the attorney general down'' by not organizing a ``more effective response'' to accusations that the dismissals were improper.

``The fact that the White House and Justice Department had been discussing this subject since the election was well-known to a number of other senior officials at the department, including others who were involved in preparing the department's testimony to Congress,'' he said in the statement. ``The focus of preparation efforts was on why the U.S. attorneys had been replaced, not how.''

The dismissals of the U.S. attorneys is drawing increasing criticism from Democrats and Republicans in Congress, who say they were misled about the reasons for the firings by Gonzales and other Justice officials. The controversy overshadowed President George W. Bush's trip to Latin America last week and is eroding support for the attorney general.

Schumer and Judiciary Committee Chairman Patrick Leahy said they want Karl Rove, Bush's top political adviser, and former White House Counsel Harriet Miers to answer questions as well. Gonzales already is scheduled to testify on April 17.

Subpoena Threat

Leahy said on ABC's ``This Week'' that he will press the committee to issue subpoenas for Rove and Miers.

``I want testimony under oath,'' Leahy, a Vermont Democrat, said. ``I am sick and tired of getting half-truths on this.''

White House Counsel Fred Fielding has been talking with lawmakers about whether Rove and Miers, among other current or former White House staff, will answer questions in the case or claim executive privilege to block their appearance.

The chairman of the House Judiciary Committee, Michigan Democrat John Conyers, has said he will seek a vote this week on issuing subpoenas to Rove and other White House officials.

Senator Arlen Specter, the senior Republican on the Judiciary committee, said he and Fielding had a ``long talk'' Friday morning about bringing Bush's aides to the Capitol. ``I think we'll know their position on Monday,'' Specter, of Pennsylvania, said on the ``Fox News Sunday'' program.

E-Mails

Copies of e-mails released over the last week by congressional committees contradicted previous assertions by Justice Department officials that the prosecutors were dismissed strictly because of their performance. There also has been conflicting information about who initiated discussion about replacing the U.S. attorneys.

Some of the e-mails disclosed that Rove inquired about replacing the U.S. attorneys as early as January 6, 2005, a month before Gonzales became attorney general. Previously, the Bush administration asserted that Miers originated the idea of firing all 93 U.S. attorneys at the start of Bush's second term.

The story ``changes every single time'' administration officials offer it, Leahy said. Specter said there are ``many conflicting assertions'' about what transpired and ``there's a good bit of investigation to be done.''

Gonzales has apologized for the way the situation was handled. Bush said March 14 he was ``not happy about it'' and had directed Gonzales to explain himself to lawmakers.

Senator John Cornyn, a Texas Republican, said Gonzales needs to lay out the facts for Congress and an investigation is warranted. The administration's explanation of the firings ``was botched from the outset,'' he said on the ABC program.

Still, he said, ``I don't believe there's any evidence that any of these people were dismissed for inappropriate reasons'' and that Democrats were conducting a ``political witch hunt'' in threatening to subpoena Rove and other White House staff.

To contact the reporter on this story: Julianna Goldman in Washington at Jgoldman6@bloomberg.net.

Last Updated: March 18, 2007 16:32 EDT