As confident as Hollywood’s lobby is that a major piece of anti-piracy legislation will see passage this year, the uncertainty is whether a vocal opposition will create any significant turbulence as it makes its way through Congress.

On Tuesday, a coalition of business and labor groups hit Capitol Hill to press the case that the Protect IP Act will save jobs, a common theme these days, as it is aimed at halting the trafficking of counterfeit and infringing goods including movies, TV shows and music on the Internet.

The legislation, which passed the Senate Judiciary Committee unanimously in May and is expected to be introduced this month in the House, is aimed at beefing up the government’s ability to seek court orders to shut down so-called “rogue” websites, those dedicated to infringing activities. It also has provisions to compel payment processors, ad networks, search engines and Internet providers to take steps to curb support of such sites.

“No one is killed by the bootlegging of a movie. However, this costs billions of dollars and hundreds of thousands of jobs,” said Paul Almeida, prexy of the department for professional employees at the AFL-CIO, at an event on Capitol Hill.

Even though the Protect IP Act so far has bipartisan support — a rarity in a polarized Congress — opponents also have been anxious to show unity on their end.

Last week, Tea Party Patriots came out against the bill, and linked to an editorial from the progressive group Demand Progress and the org Don’t Censor the Net that also expressed opposition.

In a Facebook post, the Tea Party group wrote, “Have your own website? Maybe the government will shut it down tomorrow … without any notice to you. Republicans are going to introduce this in the House, Democrats in the Senate. WHAT??? Big Labor, Hollywood, U.S. Chamber of Commerce all in this together…against you.”

Last month, more than 135 entrepreneurs, including Twitter’s Evan Williams and Zynga’s Mark Pincus, blanketed lawmakers with an open letter warning that the law will stifle innovation and chill investment. Among other things, they argued that the bill’s definition of a “rogue” site was too vague.

They also cited one of the more controversial provisions of the bill, one that allows private entities to take legal action against payment processors and ad firms that support sites trafficking in infringing material. They contended that such a provision could hobble startups with costly and lengthy litigation, a sentiment shared by the Consumer Electronics Assn.

Google’s Eric Schmidt also has expressed opposition, and there’s suspicion among showbiz lobbyists that the company is helping third-party groups form more organized opposition.

Unclear is whether the opposition will be enough to slow or stall the legislation. A spokeswoman for Rep. Lamar Smith (R-Texas), said Smith’s team is hoping to introduce its version of the bill sometime this month, with Rep. Bob Goodlatte (R-Va.), chair of a subcommittee on the Internet, among the backers.

The bill so far has 31 co-sponsors in the Senate, the most recent being Sen. Tim Johnson (D-S.D.), who added his name on Monday.

Its chief opponent is Sen. Ron Wyden (D-Ore.), citing First Amendment concerns. He put a “hold” on the legislation shortly after it cleared the Senate Judiciary Committee. Yet industry lobbyists still expect it to make it to the floor, but the question is how Senate Majority Leader Harry Reid (D-Nev.) would essentially bypass Wyden and do so by cloture vote or whether some kind of agreement will be reached.

Proponents emphasize that support goes well beyond Hollywood, where it is backed by studios and all the unions and guilds, to an unlikely alliance that includes the Chamber of Commerce and the AFL-CIO.

Political strategist Mark McKinnon moderated a panel sponsored by the Chamber on Tuesday that emphasized the legislation’s impact on the economy as well as its impact beyond Hollywood. Iowa resident Glenda Billerbeck told of a friend who unknowingly ordered tainted prescription drugs from a site offering counterfeit medicine.

Panelist Sandra Aistars, exec director of the Copyright Alliance, said criticism of the legislation is similar to opposition to past copyright legislation.

“All of these issues have been rebutted,” she said, noting the support the legislation has received from First Amendment lawyer Floyd Abrams. “It is hard to give real credence to the arguments we are hearing.”

Another panelist, Dave Tognotti, general counsel of Monster Cable, said the company devotes 25 of 500 employees to fighting sites that counterfeit its products. “It gets incrementally worse every week,” he said.

The most immediate challenge may be getting the legislation on lawmakers’ radar screens as Congress tackles deficit reduction and the sputtering economy.

McKinnon, co-chair of Arts+Labs, an org of tech and content companies, said, “This is legislation that has very broad bipartisan support. The irony is it is held up and obscured by issues that are lot more contentious.”