(Adds confirmation of vote, Portman statement)
WASHINGTON, Nov 1 (Reuters) - The U.S. Senate Commerce Committee will vote next week on a bipartisan proposal that would make it easier to penalize operators of websites that facilitate online sex trafficking, the panel said in a statement on Wednesday.
U.S. technology companies including Alphabet's Google and Facebook have long opposed legislation that would amend what is known as Section 230 of the decades-old Communications Decency Act, arguing it could thwart digital innovation and prompt endless litigation.
The vote is a setback for the internet industry, which is witnessing shifting political fortunes in Washington on a range of policy issues after decades of relatively little regulatory scrutiny.
Silicon Valley companies generally consider Section 230 a bedrock legal protection because it helps shield companies from liability for the activities of their users.
The legislation from Republican Senator Rob Portman and Democratic Senator Richard Blumenthal in August came after years of law-enforcement lobbying for a crackdown on the online classified site backpage.com, which is used for sex advertising.
The measure would make it easier for states and sex-trafficking victims to sue social media networks, advertisers and others that fail to keep exploitative material off their platforms.
In a statement, Portman said the lawmakers should "act with urgency to hold online sex traffickers accountable and give survivors the justice they deserve.
The bill has attracted bipartisan support from about a third of the Senate. A companion measure has similar backing in the House of Representatives. Republicans control both chambers.
Technology lobbyists in recent weeks have engaged in negotiations with lawmakers supportive of the bill in an attempt to narrow its impact.
(Reporting by Dustin Volz and David Shepardson; Editing by Andrew Hay and Peter Cooney)