The House will vote by year's end on legislation that would shield reporters from being forced to reveal their sources in some cases in federal court, Speaker Nancy Pelosi said Thursday.

A similar bill is headed to the full Senate after winning approval from a committee.

"This is fundamental to our democracy and fundamental to the security of our country," Pelosi, D-Calif., told The Associated Press Managing Editors. "We will bring something to the floor this year, before the end of this session."

More than 50 news outlets, including the AP, support the bill.

Despite Pelosi's announcement and the 15-2 vote in the Senate Judiciary Committee, the measure faces an uncertain future, especially in the Senate.

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.

An objection by a single senator can stall a bill in the Senate.

Patrick Fitzgerald, the U.S. attorney in Chicago and the special prosecutor in the CIA leak case, echoed that argument in a newspaper opinion piece Thursday.

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

Writing in opposition to Fitzgerald in Thursday's Washington Post, former Bush administration solicitor general Theodore B. Olson 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.