WASHINGTON - A House panel on Wednesday approved subpoenas for U.S. President Bush's political adviser, Karl Rove and other top White House aides, setting up a constitutional showdown over the firings of eight federal prosecutors.

By voice vote, the House Judiciary subcommittee on commercial and administrative law decided to compel the president's top aides to testify publicly and under oath about their roles in the firings.

The White House has refused to budge in the controversy, standing by embattled U.S. Attorney General Alberto Gonzales and insisting that the firings were appropriate. White House spokesman Tony Snow said that in offering aides to talk to the committees privately, Bush had sought to avoid the "media spectacle" that would result from public hearings with Rove and others at the witness table.

"The question they've got to ask themselves is, are you more interested in a political spectacle than getting the truth?" Snow said of the overture Tuesday by the White House via its top lawyer, Fred Fielding.

"There must be accountability," countered subcommittee Chairwoman Linda Sanchez, D-Calif.

The panel approved, but has not issued, subpoenas for Rove, former White House Counsel Harriet Miers, their deputies and Kyle Sampson, Gonzales' chief of staff, who resigned over the uproar last week.

The panel also voted to compel the production of documents related to the firings from those officials and Gonzales, Fielding and White House chief of staff Joshua Bolton. Fielding a day earlier refused to provide Congress internal White House communications on the subject.

The full Judiciary Committee would authorize the subpoenas if Chairman John Conyers of Michigan chose to do so.

The committee rejected Bush's offer a day earlier to have his aides talk privately to the House and Senate Judiciary Committees, but not under oath and not on the record.

Authorizing the subopenas "does provide this body the leverage needed to negotiate from a position of strenghth," said Rep. William Delahunt, D-Mass.

Republicans called the authorization premature, though some GOP members said they would consider voting to approve the subpoenas if Conyers promises to issue them only if he has evidence of wrongdoing.

Conyers agreed. "This (authority) will not be used in a way that will make you regret your vote."

Several Republicans said, "No" during the voice vote, but no roll call was taken.

For his part, Bush remained resolute.

Would he fight Democrats in court to protect his aides against congressional subpoenas?

"Absolutely," Bush declared Tuesday.

Democrats promptly rejected the threat. The Senate Judiciary Committee planned to approve subpoenas for the same officials on Thursday.

"Testimony should be on the record and under oath. That's the formula for true ccountability," said Judiciary Committee Chairman Patrick Leahy of Vermont.

Bush said he worried that allowing testimony under oath would set a precedent on the separation of powers that would harm the presidency as an institution.

If neither side blinks, the dispute could end in court -- ultimately the Supreme Court -- in a politically messy development that would prolong what Bush called the "public spectacle" of the Justice Department's firings, and public trashings, of the eight U.S. attorneys.

Sen. Arlen Specter, R-Pa., the Senate panel's former chairman, appealed for pragmatism.

"It is more important to get the information promptly than to have months or years of litigation," Specter said.

Bush, in a late-afternoon statement at the White House, decried any attempts by Democrats to engage in "a partisan fishing expedition aimed at honorable public servants."

"It will be regrettable if they choose to head down the partisan road of issuing subpoenas and demanding show trials when I have agreed to make key White House officials and documents available," the president said.

Bush defended Gonzales against demands from congressional Democrats and a handful of Republicans that Gonzales resign over his handling of the U.S. attorneys' firings over the past year.

"He's got support with me," Bush said. "I support the attorney general."

Democrats say the prosecutors' dismissals were politically motivated. Gonzales initially had asserted the firings were performance-related, not based on political considerations.

But e-mails released earlier this month between the Justice Department and the White House contradicted that assertion and led to a public apology from Gonzales over the handling of the matter.

The e-mails showed that Rove, as early as Jan. 6, 2005, questioned whether the U.S. attorneys should all be replaced at the start of Bush's second term, and to some degree worked with former White House Counsel Harriet Miers and former Gonzales chief of staff Kyle Sampson to get some prosecutors dismissed.

In his remarks Tuesday, Bush emphasized that he appoints federal prosecutors and it is natural to consider replacing them. While saying he disapproved of how the decisions were explained to Congress, he insisted "there is no indication that anybody did anything improper."

Nonetheless, the Senate on Tuesday voted 94-2 to strip Gonzales of his authority to fill U.S. attorney vacancies without Senate confirmation. Democrats contend the Justice Department and White House purged the eight federal prosecutors, some of whom were leading political corruption investigations, after a change in the USA Patriot Act gave Gonzales the new authority.

"What happened in this case sends a signal really through intimidation by purge: 'Don't quarrel with us any longer,'" said Sen. Sheldon Whitehouse, D-R.I., a former U.S. attorney.

The White House had signaled last week that it would not oppose the legislation if it also passed the House and reached Bush's desk.

In an op-ed in Wednesday's editions of The New York Times, one of the eight, David Iglesias of New Mexico, responded to the president: "I appreciate his gratitude for my service -- this marks the first time I have been thanked. But only a written retraction by the Justice Department setting the record straight regarding my performance would settle the issue for me."