WASHINGTON — The Senate Judiciary Committee today advanced a bill to shield reporters from being forced to reveal their sources in federal court, setting up a floor fight between supporters and Bush administration allies who believe the measure would harm national security.

The 15-2 vote sent the legislation (S. 2035) to the Senate floor, where it was expected to face more challenges if not efforts to stall or kill it. A similar measure (H.R. 2102) also awaits floor action in the House.

House Speaker Nancy Pelosi told the Associated Press Managing Editors in a speech today that she would bring the bill up for a vote by the end of the year.

“This is fundamental to our democracy and fundamental to the security of our country,” Pelosi said. More than 50 news outlets, including the AP, support the bill.

The White House and several Republican senators oppose the bill because, they say, such a policy would hobble law enforcement and efforts by intelligence officials to trace the source of leaks that could harm national security.

U.S. Attorney Patrick Fitzgerald echoed that argument today in a newspaper opinion piece.

Proponents of a federal shield law got momentum from Fitzgerald’s decision to subpoena reporters to testify against White House aide I. Lewis “Scooter” Libby in a case that grew out of Fitzgerald’s CIA leak probe. Libby was convicted of obstruction, perjury and lying to the FBI; his sentence was commuted by President Bush.

Writing in opposition to Fitzgerald in The Washington Post, Theodore B. Olson, former Bush administration solicitor general, argued for the proposed federal law, saying state shield laws have worked well.

The bill includes exemptions for cases in which investigators are tracking acts of terrorism in the U.S. and other countries. An amendment by Sen. Sam Brownback, R-Kan., would keep accused spies, agents of foreign countries and terrorists from claiming the same protections extended to journalists.