WASHINGTON — House and Senate leaders have agreed to a compromise surveillance bill that would effectively shield from civil lawsuits the telecommunications companies that helped the government wiretap phone and computer lines after the terrorist attacks of September 11, 2001, without court permission.

The House was expected to pass the bill Friday, potentially ending a monthslong standoff about the rules for government wiretapping inside America.

The House majority leader, Steny Hoyer of Maryland, said the bill “balances the needs of our intelligence community with Americans’ civil liberties and provides critical new oversight and accountability requirements.”

The issue of legal protection for telecommunications companies that participated in warrantless wiretapping has been the largest sticking point. The Senate passed a bill that immunized them from lawsuits, but the House bill was silent on the matter.

The White House had threatened to veto any bill that did not shield the companies, which tapped lines at the behest of the president and attorney general but without permission from a special court established for that purpose, the Foreign Intelligence Surveillance Court. Yesterday, the White House spokesman, Tony Fratto, said the bill met the standards sought by President Bush and that he supported it.

Warrantless wiretapping went on for almost six years until it was disclosed by the New York Times. Some 40 lawsuits have been filed against companies by people and groups who think the government illegally eavesdropped on them.

The compromise bill would have a federal district court review certifications from the attorney general saying the telecommunications companies received presidential orders telling them wiretaps were needed to detect or prevent a terrorist attack. If the paperwork were in order, the judge would dismiss the lawsuit.

Rep. Roy Blunt of Missouri, the second-ranking Republican, predicted all the cases would go away.