WASHINGTON — When Jack Valenti walked the halls of Congress, friends by the dozen gripped, grinned and took note of what was worrying the movie industry’s dapper chief lobbyist.

Christopher J. Dodd now fills Mr. Valenti’s shoes. But he stays out of those halls, thanks to restrictions on his ability to lobby Congress until 2013.

It just cost him a big one.

A major push by copyright holders — including those in the Motion Picture Association of America, of which Mr. Dodd is chairman — for a tough federal law to control foreign online piracy collapsed this week under stiff resistance from technology companies and their allies.

On Wednesday, as Web sites expressed opposition to the legislation, important lawmakers withdrew their support, leaving Mr. Dodd and his associates scrambling to find what could be salvaged.