Senate Democrats said Tuesday they would filibuster legislation, backed by the White House and the National Rifle Association (search), that would protect gun manufacturers and sellers from lawsuits arising from the criminal or unlawful use of their products.

Opponents "will do everything we can to stop this shameful piece of legislation from becoming law," said Sen. Jack Reed, D-R.I.

The legislation passed the House last month on a 285-140 vote with nearly one-third of Democrats supporting it. The White House said in a statement the measure "would help prevent abuse of the legal system and help curb the growing problem of frivolous lawsuits in the United States."

Supporters argue it would stop a rash of lawsuits inspired by legal action against the tobacco industry and aimed at winning large rewards or bankrupting the gun industry. Since 1998, at least 33 municipalities, counties and states have sued gunmakers, many claiming that manufacturers allowed weapons to reach criminals because of irresponsible marketing.

The Senate equivalent, offered by Sen. Larry Craig, R-Idaho, has 52 sponsors. Reed said the battle would be over supporters getting the 60 votes needed to end a filibuster and bring the bill to a final vote.

Washington "has a rich and sordid history of special interest sleaze," said Sen. Dick Durbin, D-Ill. "The gun industry bill merely retires the trophy. This is as bad as it gets."

Reed said that, along with filibustering the bill, opponents might try to amend it to close gun show loopholes on purchasing waiting periods, add safety lock language and toughen criminal background checks. No date has been set for floor debate.

Sen. Barbara Mikulski, D-Md., said that under the legislation, the families of the victims of last year's Washington-area sniper (search) attacks would be barred by Congress from suing the Tacoma, Wash., gun shop that sold the gun to the alleged snipers. The shop has no record of that sale or the sales of more than 200 other guns, and the families believe it was negligent.

But Chris Cox, chief lobbyist for the NRA, said the bill is aimed at protecting legal manufacturers from being held responsible for the illegal actions of criminals. "It doesn't protect those who break state or federal laws," he said. "It doesn't close the door to anyone" filing claims against wrongdoers.

He said passing the gun manufacturers' liability bill was the NRA's top legislative priority this year. The NRA has askedChief Justice Willliam H. Rehnquist (search) to block parts of a lower court ruling on campaign finance law, citing the group's inability under the ruling to run ads promoting the legislation.

The liability bill is one of a few gun-related issues to arise in a Congress where gun-control advocates, faced with a Republican president and a GOP-controlled House and Senate, are on the defensive.

President Bush, in a rare divergence from the NRA, has given his qualified support for extending the 10-year ban on assault weapons enacted in a 1994 law. House Majority Leader Tom DeLay, R-Texas, cautioned Democrats on Tuesday they would not have the votes in the House for any attempt to expand the weapons listed under the ban.

Sen. Orrin Hatch, R-Utah, also held hearings Tuesday of the Judiciary Committee he chairs to discuss Project Safe Neighborhoods, a program initiated by the Bush White House two years ago to crack down on gun crimes.

He said the hiring of more prosecutors and the focus on crimes involving guns has resulted in a 40 percent increase in federal gun prosecutions, with more than half of convicted gun criminals getting more than five years in prison.