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.

In an interview Thursday, Mr. Dodd said he would welcome a summit meeting between Internet companies and content companies, perhaps convened by the White House, that could lead to a compromise. On Friday, Senator Harry Reid indefinitely postponed a cloture vote scheduled for Tuesday in the Senate, which appears to promise the death of the legislation in its current form.

“The perfect place to do it is a block away from here,” said Mr. Dodd, who pointed from his office on I Street toward 1600 Pennsylvania Avenue.

But the startlingly speedy collapse of the antipiracy campaign by some of Washington’s savviest players — not just the motion picture association, but also the United States Chamber of Commerce and the Recording Industry Association of America — signaled deep changes in antipiracy lobbying in the future. By Mr. Dodd’s account, no Washington player can safely assume that a well-wired, heavily financed legislative program is safe from a sudden burst of Web-driven populism.

“This is altogether a new effect,” Mr. Dodd said, comparing the online movement to the Arab Spring. He could not remember seeing “an effort that was moving with this degree of support change this dramatically” in the last four decades, he added.

That shift was exposed this week partly because Mr. Dodd found himself in a political knife fight while being forced to sheathe his most powerful weapon: 36 years of personal relationships with a Congress in which he had served as a representative and then senator since 1975, before joining the motion picture association last March.

Under legislation passed in 2007, Mr. Dodd is barred from personally lobbying Congress for two years after leaving office. Hired as the consummate Washington insider to carry the film industry’s banner on crucial issues like piracy, Mr. Dodd ended up being more coach than player. He helped devise a strategy that called for his coalition to line up a strong array of legislative sponsors and supporters behind two similar laws — the Stop Online Piracy Act in the House, and the Protect I.P. Act in the Senate — and then to move them through the Congress quickly before possible opposition from tech companies could coalesce.

But slow pacing gave the Internet and free speech advocates time to wake up and mobilize, turning what might have been a relatively simple exercise for Mr. Dodd and his allies into a bitter struggle. The delays violated a cardinal rule among professional lobbyists, who generally believe the worst enemy of a proposed law is the legislative clock.

Mr. Dodd said that the entire industry was surprised by the intensity of the objections that arose in the last couple of weeks. “This was a whole new different game all of a sudden,” he said. “This thing was considered by many to be a slam dunk.”

Data shows that copyright holders and supporters of the bills outspent opponents substantially in the early stages of the debate. But by many accounts the tech industry has stepped up its lobbying efforts in recent weeks. New spending reports expected shortly indicate whether the balance has shifted.

The Senate vote on Tuesday will show whether opponents like Ron Wyden, Democrat of Oregon, have succeeded in derailing that chamber’s version of the law.

On Thursday, however, Mr. Dodd appeared to have all but thrown in the towel on the bills in their current form, and was talking about lessons learned. He acknowledged his side had committed a misstep by allowing Hollywood to become the face of laws that were intended to protect not just movies, but also more mundane products — for instance, home smoke alarms — that are frequently counterfeited abroad, sometimes with disastrous effects.

“In terms of public perception, I’m Exhibit A,” said Mr. Dodd, who spent last weekend hobnobbing with stars at the Golden Globes. “This is seen as a red carpet business.”

It was a further problem, he said, that Hollywood’s writers, directors, producers and blue-collar workers — whose unions squarely backed the new law — never personally campaigned in a way that might have helped to counter the Web assault.

“There’s a disconnect between the business interests and the politics of Hollywood,” Mr. Dodd said, meaning that the film industry and its denizens provided money for many campaigns, including those of Mr. Obama, without pushing its issues to the fore.

Mr. Wyden said the public resistance confirmed his longstanding belief that the measures would become wildly unpopular once people saw their potential for censoring Web sites and unleashing litigation against entrepreneurs, both large and small.

“I will use every ounce of my strength to fight” to stop PIPA in next week’s procedural vote, said Mr. Wyden, who has been pushing what he said was a less intrusive alternative. The fight has been a challenge for Mr. Dodd in other ways as well. A silver-haired 67-year-old, Mr. Dodd risks looking like a scold in public appearances that find him lecturing opponents about damage to the economy, including some $58 billion in estimated annual losses to copyright thieves.

In his office on Thursday, he pointed his finger while recalling how he had recently admonished high school-age students on a Massachusetts film set. The next time they are tempted to steal a film, he told them, think about the makeup artists and grips whose jobs are at stake.

“I think Chris Dodd has done a spectacular job,” said Jim Gianopulos, co-chairman of Fox Filmed Entertainment, who spoke by telephone on Thursday. “He’s been unable to do direct lobbying, but as a strategist, he’s been superb,” said Mr. Gianopulos. Misinformation about the antipiracy bills had complicated a campaign that is not yet over, he said.

While Mr. Dodd is barred from Congressional contact, he has had a free hand in lobbying the White House and federal agencies. On Saturday, however, the Obama administration dealt his efforts a blow by announcing publicly, in response to online petitions, that it had reservations about a provision in the proposed laws that called for blocking user access to offending sites.

Mr. Dodd spoke with barely concealed anger at what he called a “really gratuitous” statement delivered by what he had presumed was a sympathetic administration, which came after the blocking provisions had effectively been killed in Congress.

The real message, said Mr. Dodd, may be that further change is in order for the motion picture association, which represents Walt Disney Studios, Paramount Pictures, Sony Pictures Entertainment, 20th Century Fox, Universal Studios and Warner Brothers. The group, he said, lost focus and energy after Mr. Valenti’s retirement in 2004.

The companies, Mr. Dodd said, are “rethinking everything,” not just about the bills, but about their relationship with an estranged Silicon Valley.

That need for rapprochement, he said, “has come home in a way that no rhetoric of mine could express.”