"The moment is ripe to move the patent system forward to meet the challenges of the 21st century," said Rep. Howard Berman, D-Calif., a lead sponsor. "Serious flaws have to be fixed for our system to remain robust now and long into the future."

But with the legislation continuing to engender opposition from the White House and many industry groups, including pharmaceutical and biotechnology companies, Berman acknowledged that further adjustments will be needed before it goes to the president. The Senate Judiciary Committee has approved a similar bill offered by that panel's chairman, Sen. Patrick Leahy, D-Vt., and Senate leaders are committed to bringing it to the floor this fall.

House GOP leaders balked at the vote, urging further negotiations. "While our patent system is in need of reform, we are very concerned that the bill in its present form picks winners and losers among industries with different business models in a way that has never before been attempted in patent law or practice," wrote Republican leader John Boehner, R-Ohio, and GOP Whip Roy Blunt, R-Mo.

Among supporters are consumer groups, major high-tech companies, financial associations and farm groups.

Late tweaking of the measure's language did persuade several former opponents to shift their positions.

William Samuel, the AFL-CIO's legislative director, said the bill had been improved in key areas, although "we reserve judgment at this point on final enactment."

The Association of American Universities said in a letter Thursday that it supported bringing the bill to a vote, although it still had concerns that "need to be addressed."

Both the union and the universities were looking at provisions that would tighten the awarding of damages in infringement cases, based in some cases on a patent's overall value to the product, while limiting windfall damage awards.

Bill supporters cited a $1.5 billion jury verdict against Microsoft Corp., later overturned, as an example of the current system's excesses.