Updated

Locked in a standoff with the White House, House Democrats on Tuesday maintained their refusal to shield from civil lawsuits telecommunications companies that helped the government eavesdrop on their customers without a secret court's permission.

But they offered the companies an olive branch: the chance to use classified government documents to defend themselves in court.

House Democratic leaders unveiled a bill that they hoped would bridge the gap between the electronic surveillance bill passed by the Senate last month and a rival version the House approved last fall.

Both bills are attempts to update the 1978 Foreign Intelligence Surveillance Act, the law that dictates when the government needs court permission to conduct electronic eavesdropping inside the United States. The law has taken on particular importance in the global effort to thwart terrorists since the 2001 attacks on the United States.

The most contentious difference between the two bills is whether they grant legal immunity to telecommunications companies that helped the government wiretap phone and computer lines after the Sept. 11 terrorist attacks without first getting approval from the FISA court. Congress created that court 30 years ago to prevent government abuse of its surveillance powers.

The Senate bill would provide full immunity to the telecommunications companies. The House bill includes no such provision.

The compromise proposed Tuesday by House Democratic leaders is expected to be brought to the floor for a vote Thursday. It would allow the roughly 40 lawsuits that are pending against the companies for their participation in the secret wiretapping program to go forward.

"We are not going to cave in" on immunity, said House Judiciary Committee Chairman John Conyers, D-Mich.

The companies are hamstrung from defending themselves in court, however. The Bush administration is invoking the "state secrets" privilege to block the companies from revealing secret documents that might bolster their argument that the eavesdropping program was legal.

The House compromise bill would encourage the federal district judge hearing the telecommunications lawsuits to review those classified documents in secret to determine whether the companies acted legally.

Judges in criminal cases often hear classified evidence in secret, but judges in civil cases do not, said House Majority Leader Steny Hoyer, D-Md.

President Bush has vowed to veto any bill that does not grant the companies full retroactive immunity from lawsuits.

Democratic leaders say they are trying to strike a balance between protecting the country against terrorist attacks and protecting civil liberties.

The House compromise bill would also create a bipartisan commission, modeled after the 9/11 Commission, to investigate the so-called warrantless wiretapping program.