Eight US lawmakers have withdrawn their support for anti-piracy laws, after "blackout" protests on thousands of internet sites.
Online encyclopaedia Wikipedia argues that proposed laws would damage internet freedom and temporarily closed its English-language website for 24 hours on Wednesday in protest. Blog service WordPress also blocked its content.
Wikipedia and other sites are opposed to the US Stop Online Piracy Act (Sopa) and Protect Intellectual Property Act (Pipa) being debated by Congress.
The bills are intended to curb internet piracy by cutting off access to overseas websites illegally offering American content such as films and music, the BBC reports.
Legislators sought to curb the distribution of pirated and counterfeit products by giving the courts the power to force search engines to de-list pirate sites.
But in the Senate, the Protect Intellectual Property Act bill that looked close to passing now appears to be in trouble. Two of its co-sponsors, Marco Rubio from Florida and Roy Blunt from Missouri, are among those backing away.
In the House of Representatives, the Speaker John Boehner has said that there is now a lack of consensus about the proposed law.
The list of senators no longer supporting Pipa includes Mr Rubio and Mr Blunt, and Utah Senator Orrin Hatch, all Republicans, as well as Democrat Ben Cardin of Maryland.
In the House of Representatives, Republicans Ben Quayle of Arizona, Lee Terry of Nebraska and Dennis Ross of Florida said they were no longer supporting the Stop Online Piracy Act (Sopa), joining Pennsylvania Democrat Tim Holden.
Media firms argue that the new laws are vital to protect the movie and music industries against the theft of their products.
Hollywood also supports the bills, but Wikipedia and other internet giants like Google and Yahoo complain that the draft laws would empower the US government to censor the internet through techniques similar to those used in China and Iran.