A Republican-led bill to shield gun manufacturers and distributors from lawsuits arising from gun crimes passed its first Senate test Wednesday, but Democrats plan to complicate its future by forcing votes on extending an assault weapons ban and requiring background checks on purchasers at gun shows.   

The Senate, with a 75-22 test vote, showed that there is enough support from both parties to get gunmaker immunity legislation through, but Democrats plan to try and add their gun legislation to the package before it heads to the House.

Democrats want "provisions that will close the gun show loophole, that would reauthorize the ban on assault weapons," said Sen. Jack Reed, D-R.I. "We should require effective safety locks on handguns. We should improve the National Instant Criminal Background Check (search) system."

Those measures are less popular with the Senate's GOP majority and could cause problems for the bill if included. The GOP-controlled House already has said it does not plan to approve an extension of the assault weapons ban.

"Some of our colleagues already announced they intend to play politics with this bill," said Sen. Larry Craig (search), R-Idaho, one of the legislation's main sponsors.

The White House — which supports the gunmaker immunity bill, extending the assault weapons ban and closing the gun show loophole — nonetheless called on the Senate to pass the legislation without amendments.

"The administration urges the Senate to pass a clean bill, in order to ensure enactment of the legislation this year," the White House said in a statement. "Any amendment that would delay enactment of the bill beyond this year is unacceptable."

Republicans, along with some Senate Democrats, have been pushing for the gun immunity legislation for some time. Gun advocates say firearm makers shouldn't be forced to spend millions of dollars fighting off lawsuits designed to win large rewards and bankrupt them for making legal products.

Democrats including Senate Minority Leader Tom Daschle (search) of South Dakota agreed to back the legislation after gun supporters accepted a specification that firearms manufacturers and distributors would not be immune to lawsuits involving defective products or illegal sales.

But getting the 1994 assault weapons prohibition renewed also is Democratic priority this year. They picked up support Tuesday from GOP Sens. John Warner of Virginia, Mike DeWine of Ohio and Lincoln Chafee of Rhode Island.

"Although I voted against the ban a decade ago, over the past 10 years it has reduced crime dramatically and has made our streets safer," Warner said. "The legislation also has protected the rights of gun owners better than many of us predicted."

The three GOP senators' support does not guarantee the amendment's approval in the Senate, but "this gives the effort to renew the assault weapons ban new momentum," said Sen. Dianne Feinstein (search), D-Calif., sponsor of the original assault weapons ban.