WASHINGTON - The fight over documents has gone to red alert.The White House acknowledges it cannot find four years' worth of e-mails from chief political strategist Karl Rove. The admission has thrust the Democrats' nemesis back into the center of attention and poses a fresh political challenge for President Bush.

The administration has acknowledged that some e-mails missing from Rove's Republican party account may relate to the firing of eight U.S. prosecutors last year. The Democratic-run Congress is investigating whether the firings resulted from political pressure by Attorney General Alberto Gonzales and the White House.

Target: Rove For Democrats, the missing Rove e-mails is one more chance to pound away at their favorite target, the architect of Bush's 2000 and 2004 presidential victories and all-around White House political fixer.

Senate Judiciary Committee Chairman Patrick Leahy, D-Vt., has compared the missing e-mails to the 18-minute gap on President Nixon's Watergate tapes. Sen. Charles Schumer, D-N.Y., says the White House message to Congress is: "We are stonewalling."

The White House chalks it up to just another outbreak of Democratic Rove rage. "My experience has been that any time Karl Rove's name is mentioned, it adds to the ammunition, regardless of merit," White House deputy press secretary Dana Perino said.

Only Dick Cheney raises the same kind of anger - and there is not much they can do about the vice president, short of impeachment.

Miers, Rove testimony in question The Rove connection is sure to be raised when Gonzales testifies Tuesday before Leahy's committee. His appearance, Democratic and Republican lawmakers say, may determine whether the longtime Bush friend can hold onto his job.

Democrats plan to focus on the Justice Department's contradictory statements about the firings and Gonzales' shifting explanations of his own role.

Democrats now are seeking Rove's sworn public testimony in their investigation of dismissed U.S. attorneys. So far, the White House has agreed only to off-the-record interviews for Rove and former White House counsel Harriet Miers with committee members.

Department documents turned over to Congress suggested that Rove and Miers had an early role in planning the firings, despite initial White House statements to the contrary.

Democrats have threatened to issue subpoenas. But, due to the constitutional separation of executive and legislative powers, it is not clear they can force Rove to testify.

"He's been a pet symbol to Democrats," said Fred Greenstein, professor emeritus of politics at Princeton University. "It's clear that he is very important to Bush and that the president takes him very seriously, even if the 2008 election outcome would be totally unaffected by dropping Rove."

Despite Rove's reputation as a political grand master, there is not exactly a rush to his door among the current large field of Republican presidential hopefuls.

Previous attempts Democrats have had Rove in their cross hairs before; he always has slipped away.

He was implicated in the CIA leak case as someone who had passed on the identity of CIA undercover agent Valerie Plame to reporters. But he never was charged and never called to testify in the trial of I. Lewis "Scooter" Libby, Cheney's former chief of staff. Libby was convicted of perjury and obstruction of justice and is awaiting sentencing.

Rove also managed to emerge unscathed from investigations of administration and congressional ties to convicted lobbyist Jack Abramoff.

If Rove deliberately deleted e-mails relating to the firing of the prosecutors, Democrats suggest, he could run afoul of a 1978 law that requires the White House to keep documents that relate to presidential actions, decisions and deliberations.

Administration fatigue Republican strategist Rich Galen says Democrats could make the same mistakes that Republicans made under House Speaker Newt Gingrich, R-Ga., in going after President Clinton after winning control of the House.

"That's what got us in big trouble in 1998 (midterm elections, when Republicans lost seats) and ultimately cost Newt his job as speaker. We so solely focused on going after Bill Clinton that people said, in essence, `We hired you to solve stuff - and not to spend all day, every day, trying to figure out how to make Bill Clinton's life miserable,'" said Galen, who worked for Gingrich when he was speaker.

Rove's lawyer, Robert Luskin, denies that his client deleted his own e-mails from a Republican-sponsored computer system. "His understanding, starting very, very early in the administration was that those e-mails were being archived," Luskin said.

Ross Baker, a political scientist at Rutgers University, said the controversy over the missing Rove e-mails is another sign of "the downward spiral of an old, tired administration."

It comes as public support for the war in Iraq continues to erode, Bush's approval ratings are in the mid-30s and the administration is embroiled in multiple scandals and ethics investigations.

"They've got serious combat fatigue after six years in office," said Baker. "The forces there are getting very thin."

© 2007 The Associated Press.