Daniel Terdiman/CNET

The broad support in the U.S. government for two controversial antipiracy bills appears to be evaporating.

The latest string of setbacks for supporters of the bills came Saturday when Darrell Issa (R-Calif.), chairman of the Oversight committee in the U.S. House of Representatives, said that he was promised by Majority leader Eric Cantor (R-Va.) that a vote on the Stop Online Piracy Act (SOPA) will not occur "unless there is consensus on the bill."

"While I remain concerned about Senate action on the Protect IP Act [a similar bill to SOPA introduced into the Senate last year], I am confident that flawed legislation will not be taken up by this House," Issa said in a statement, according to the blog The Hill. "Majority Leader Cantor has assured me that we will continue to work to address outstanding concerns and work to build consensus prior to any antipiracy legislation coming before the House for a vote."

After it was learned that a vote on SOPA might get held up in the House, supporters of stronger antipiracy legislation suffered an even bigger blow when the White House, which has been a strong ally of the entertainment sector on antipiracy issues, went public with concerns about some of the linchpin provisions in SOPA and the Protect IP Act (PIPA).

SOPA and PIPA are backed by a wide range of copyright owners, including the six Hollywood film studios and the four major record companies. The bills would hand the U.S. Justice Department the ability to cut off access in the United States to Web sites based overseas accused of trading in pirated or counterfeit materials. It would also give the government the power to force credit card companies, online advertisers, and Internet service providers to cut off ties with accused pirates.

Opponents, which include a wide number of technology companies as well as free-speech advocates, say SOPA and PIPA would threaten free speech and stifle innovation.

The latest developments signal a shift in momentum. Last year, copyright owners could boast strong bipartisan support in both houses of Congress and a powerful friend in the White House. Now, after SOPA and PIPA opponents mounted a vigorous campaign against the bills, they have seen lawmakers give up on the Domain Name System (DNS) provisions in both pieces of legislation--the provisions that would have given the government the aforementioned power to force ISPs to block access to alleged overseas pirate sites.

Just how many more concessions opponents can obtain is unclear, but they don't appear to have any intention of letting up now. An important test for both sides will come January 24, when the Senate is scheduled to hold a vote on PIPA.

Congressional support for the bills appeared to be waning in recent weeks as the technology sector began circulating petitions, criticizing the bills on scores of blogs and news sites and e-mailing individual lawmakers. Then, on Thursday, Sen. Patrick Leahy, announced he would remove the DNS provision from PIPA.

The following day, the DNS requirement appeared to suffer a death blow when Rep. Lamar Smith (R-Texas), chairman of the House Judiciary Committee, announced he would follow Leahy in removing the same provision from SOPA.

In another worrisome sign for copyright owners, support in the Senate appears to be weakening. This week, six Republican senators wrote to Majority Leader Harry Reid and asked him to postpone the vote on PIPA.

"We have increasingly heard from a large number of constituents and other stakeholders with vocal concerns about possible unintended consequences of the proposed legislation," wrote the senators, including Orrin Hatch (R-Utah), Jeff Sessions (R-Ala.), and Mike Lee (R-Utah). The concerns include "breaches in cybersecurity, damaging the integrity of the Internet, costly and burdensome litigation, and dilution of First Amendment rights."

One of the senators who penned the letter is Charles Grassley (R-Iowa) one of the PIPA's co-sponsors.

The good news for proponents of tougher antipiracy laws came from Senate Majority Leader Harry Reid (D-Nev.) and his reply to the request by the six senators.

"This is an issue that is too important to delay," Reid wrote in denying their request, according to a story in the blog Politico (registration required). He acknowledged that PIPA is not perfect and said he would welcome "an open amendment process, [to] ensure that all Senators have an opportunity to raise their concerns and to work together to forge a compromise."

It's hard to tell which one of the setbacks is the most damaging to copyright owners. Surely, the White House's decision to publicly pick apart the legislation when SOPA and PIPA are both under siege is certainly a strong candidate. In the past two years, White House officials have vowed to step up the government's antipiracy efforts. U.S. Vice President Joe Biden during a press conference compared online piracy to "smash-and-grab" theft.

The White House's statement on the bills was written by Victoria Espinel, and two other White House technology experts.

Not only was the White House critical of the now-dead DNS provisions but it also called for legislation that protected against online censorship and included "strong due process."

Critics of the bills have long argued that the proposals fail to provide Web site operators accused of piracy with a chance to defend themselves in a court of law--a basic right. Supporters of the bills have dismissed the complaints, but President Barack Obama's staff, in their letter, added credibility to the criticism.

The White House, however, did not come out directly against the proposed legislation and reaffirmed its commitment to fighting piracy.

"Online piracy is a real problem that harms the American economy," the White House said in the statement, "and threatens jobs for significant numbers of middle class workers and hurts some of our nation's most creative and innovative companies and entrepreneurs. It harms everyone from struggling artists to production crews and from start-up social media companies to large movie studios...existing tools are not strong enough to root out the worst online pirates beyond our borders."

The White House also called on supporters and opponents of the bills to come up with a joint plan to fight copyright violations as well as protect the Internet and free speech.