Updated

House Speaker Nancy Pelosi said Friday she intends to sue the Bush administration in response to Attorney General Michael Mukasey's refusal to refer the House's contempt citations against two of President Bush's top aides to a federal grand jury.

Pelosi, in a written statement, accused the administration of "continuing to politicize law enforcement."

"The House has already provided authority for the Judiciary Committee to file a civil enforcement action in federal district court and the House shall do so promptly," she said. "As public officials, we take an oath to uphold the Constitution and protect our system of checks and balances and our civil lawsuit seeks to do just that."

The White House countered with its own pledge to fight House leaders to the end.

"If Speaker Pelosi insists on taking this case to a court, they will be met with opposition at the courthouse door and at every step of any court case," White House Deputy Press Secretary Tony Fratto said. "The president's case is strong, and he would not have asserted executive privilege if he did not believe he would prevail in the face of attempts to challenge his decision."

Pelosi's statement closely followed Mukasey's letter to her Friday saying White House Chief of Staff Josh Bolten and former presidential counsel Harriet Miers were right in refusing to provide Congress White House documents or testify about the firings of federal prosecutors.

Mukasey says they committed no crime.

"The department will not bring the congressional contempt citations before a grand jury or take any other action to prosecute Mr. Bolten or Ms. Miers," Mukasey wrote House Speaker Nancy Pelosi.

The House voted two weeks ago to cite Bolten and Miers for contempt of Congress and seek a grand jury investigation. Most Republicans boycotted the vote.

Pelosi requested the grand jury investigation on Thursday and gave Mukasey a week to reply. She said the House would file a civil suit seeking enforcement of the contempt citations if federal prosecutors declined to seek misdemeanor charges against Bolten and Miers.

Mukasey took only a day to get back to her. But he had earlier joined his predecessor, Alberto Gonzales, in telling lawmakers they would refuse to refer any contempt citations to prosecutors because Bolten and Miers were acting at Bush's instruction.

A civil suit would drag out a slow-motion crawl to a constitutional struggle between a Democratic-run Congress and a Republican White House that has been simmering for more than a year. Any court showdown might not occur until Bush is out of office in 14 months.

Democrats say Bush's instructions to Miers and Bolten to ignore the House Judiciary Committee's subpoenas was an abuse of power and an effort to block an effort to find out whether the White House directed the firing of nine U.S. attorneys in 2006 for political reasons.

Republicans call the whole affair a political game and walked out of the House vote on the contempt citations in protest.

The 223-32 House vote on a resolution approving the contempt citations Feb. 14 was the first of its type in 25 years. The White House pointed out that it was the first time that such action had been taken against top White House officials who had been instructed by the president to remain silent to preserve executive privilege.

In his letter, received by the House early Friday evening, Mukasey pointed out that not only was Miers directed not to testify, she also was immune from congressional subpoenas and was right to not show up to the hearing to which she had been summoned.

"The contempt of Congress statute was not intended to apply and could not constitutionally be applied to an executive branch official who asserts the president's claim of executive privilege," Mukasey wrote, quoting Justice policy.

"Accordingly," Mukasey concluded, "the department has determined that the noncompliance by Mr. Bolten and Ms. Miers with the Judiciary Committee subpoenas did not constitute a crime."

The Associated Press contributed to this report.