Many legislators and campaigners are unsatisfied with the “watered-down” version of the anti-surveillance bill that passed the House of Representatives with a majority of both Republicans and Democrats, 303 to 121, on Thursday.

The USA Freedom Act is the first piece of legislation “aimed specifically at curbing U.S. surveillance abuses revealed by Edward Snowden,” The Guardian reports. When he accepted the Ridenhour Prize for Truth-Telling at the National Press Club in Washington, D.C., on April 30, Snowden described the legislation as “the only act that really starts to address these concerns.”

Last-minute efforts by lawmakers loyal to the intelligence establishment weakened key language in the bill. The revision lost the support of several influential members of the House Judiciary Committee who had previously voted for it, including Republicans Darrell Issa, Ted Poe and Raul Labrador and Democrat Zoe Lofgren.

Mark Jaycox, a legislative analyst with the Electronic Frontier Foundation, said: “The bill is littered with loopholes. The problem right now, especially after multiple revisions, is that it doesn’t effectively end mass surveillance.”

Zeke Johnson, director of Amnesty International USA’s security and human rights program, declared the House had “failed to deliver serious surveillance reform.”

“People inside and outside the U.S. would remain at risk of dragnet surveillance,” he continued. “The Senate should pass much stronger reforms ensuring greater transparency, robust judicial review, equal rights for non-U.S. persons, and a clear, unambiguous ban on mass spying. President Obama need not wait. He can and should implement such safeguards today.”

The Guardian quoted Sen. Patrick Leahy, chair of the Senate Judiciary Committee and lead Democratic author of the Freedom Act, at length:

[Leahy]said that the actions of the house in passing it was an “important step towards reforming our nation’s surveillance authorities”which “few could have predicted less than a year ago.”

However, in a statement issued on Thursday, Leahy expressed disappointment that the bill, which he had introduced jointly with Sensenbrenner in October, had been diluted.

He said: “Today’s action in the House continues the bipartisan effort to restore Americans’ civil liberties. But I was disappointed that the legislation passed today does not include some of the meaningful reforms contained in the original USA Freedom Act. I will continue to push for these important reforms when the Senate judiciary committee considers the USA Freedom Act next month.”

Sen. Ron Wyden, an Oregon Democrat who has long opposed NSA surveillance and objected to the form of the bill passed Thursday, said the Senate version of the bill remained strong and he hoped that its provisions could be maintained. The Guardian quoted him as saying, “I am gravely concerned that the changes that have been made to the House version of this bill have watered it down so far that it fails to protect Americans from suspicionless mass surveillance.”

Observers say the size of the rebellion and the senior status of some of the rebels may help efforts to improve language in the legislation as it is deliberated by the Senate.