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.

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.