President George W. Bush has asserted executive privilege over documents sought by the Democratic-led Congress related to the sackings of federal prosecutors last year.
Presidential counsel Fred Fielding said said in a letter to Congress that the president had decided to assert executive privilege and that the White House would not produce any documents in response to the subpoenas.
The White House letter, addressed to Senator Patrick Leahy and Representative John Conyers, the Democratic chairmen of the congressional judiciary committees, was in response to subpoenas it received this month requesting documents related to the firings of several US attorneys last year.
Democrats who took control of Congress this year say the firings were politically motivated and have sought White House testimony and documents in a controversy that has led to bipartisan calls for Attorney General Alberto Gonzales to step down.
Mr Bush has steadfastly backed Mr Gonzales, however, and the showdown could result in a lengthy court fight.
"Increasingly, the president and vice president feel they are above the law - in America no one is above law," Mr Leahy said in a statement.
"This White House cannot have it both ways. They cannot stonewall congressional investigations by refusing to provide documents and witnesses, while claiming nothing improper occurred," he said.