WASHINGTON (CNN) -- The Senate Judiciary Committee cemented a showdown with the White House Thursday when it authorized its chairman to issue subpoenas to force key White House aides to testify about what they know regarding the firings of eight U.S. attorneys.

That power, though, does not mean that subpoenas will be issued; rather that they could be if the aides in question do not voluntarily appear before the committee.

President Bush has said that his top political adviser, Karl Rove, former White House counsel Harriet Miers and their two top deputies could be interviewed by congressional investigators -- but with no oath and no transcript of the proceedings.

White House spokesman Tony Snow said that if lawmakers decide to use subpoenas to force testimony, the president's offer is off the table.

Republican members of the Senate Judiciary Committee had urged the panel to hold off on even authorizing the use of subpoenas, arguing that the aides under scrutiny should be allowed to be interviewed under the White House conditions.

If the committee is not satisfied with their responses, they could then use the legal tool to compel further testimony, GOP committee members said.

Ranking Republican member Sen. Arlen Specter of Pennsylvania also suggested they try to broker a compromise with the White House on the deal.