Congressional opposition to the NSA's bulk surveillance on Americans swelled on Tuesday as the US House prepared to vote on restricting the collection of US phone records and a leading Senate critic blasted a "culture of misinformation" around government surveillance.

Republican congressman Justin Amash prevailed in securing a vote for his amendment to a crucial funding bill for the Department of Defense that "ends authority for the blanket collection of records under the Patriot Act." The vote could take place as early as Wednesday evening.

"The people have spoken through their representatives," Amash told the Guardian on Tuesday. "This is an opportunity to vote on something that will substantially limit the ability of the NSA to collect their phone records without suspicion."

It will be the first such vote held by Congress on restricting NSA surveillance after the revelations from ex-contractor Edward Snowden, published in the Guardian and the Washington Post, that detailed a fuller picture of the surveillance authorities than officials had publicly disclosed – something blasted in a fiery Tuesday speech by Senator Ron Wyden, a prominent Democratic critic of the surveillance programs.

In a sign of how crucial the NSA considers its bulk phone records collection, which a secret surveillance court reapproved on Friday, its director, General Keith Alexander, held a four-hour classified briefing with members of Congress. Alexander's meeting was listed as "top-secret" and divided into two two-hour sessions, the first for Republicans and the second for Democrats. Staffers for the legislators were not permitted to attend.

Amash, who attended the briefing, described it as cordial but declined to give specifics about what was discussed. "I don't believe anyone's mind was changed one way or the other," he said.

Representatives for Alexander did not respond to a request for comment.

Amash's amendment, supported by a Michigan Democrat, John Conyers, unexpectedly made it through the House rules committee late on Monday night, a feat for which the second-term legislator credited House speaker John Boehner.

The amendment would prevent the NSA, the FBI and other agencies from relying on Section 215 of the Patriot Act "to collect records, including telephone call records, that pertain to persons who are not subject to an investigation under Section 215."

Debate over Amash's amendment is expected for late Wednesday, with a vote coming either Wednesday night or early Thursday.

Its outcome is difficult to predict. The vote by itself will not restrict the surveillance, it would simply include Amash's amendment in the annual Defense appropriations bill, which the House is considering this week; the Senate must also approve the bill before it goes to President Obama's desk. There is deep, bipartisan support for the domestic phone-records collection in the House intelligence committee and deep, bipartisan opposition for it in the House judiciary committee.

Yet Wyden, one of the leading Senate critics of the NSA's bulk domestic surveillance, called it "unquestionably good" that Congress was openly debating the extent of the collection of Americans' phone records.

"It is another step, as I've outlined, in the march to a real debate," Wyden said during a speech at the Center for American Progress, a thinktank aligned with the Obama administration. "We wouldn't have had that seven, eight weeks ago."

Wyden described the bulk surveillance of Americans' phone records as a "human relationship database," and described a "culture of misinformation" around it from government officials as a threat to American democracy, warning that "unless we seize this unique moment" to weaken both, "we will all live to regret it."

"The combination of increasingly advanced technology with a breakdown in the checks and balances that limit government action could lead us to a surveillance state that cannot be reversed," Wyden said.

Wyden, in a wide-ranging speech, reiterated a warning that the authorities government officials believe themselves to have under Section 215 of the Patriot Act might also allow the NSA or FBI to retain bulk medical records, gun purchase records, financial transactions, credit card data and more. "Intelligence officials have told the press that they currently have the legal authority to collect Americans' location information in bulk," he noted

Wyden assailed administration and intelligence officials for describing their surveillance as limited in public remarks while secretly briefing legislators about their broad scope.

"The public was not just kept in the dark about the Patriot Act and other secret authorities," Wyden said. "The public was actively misled."

On July 2, James Clapper, the US director of national intelligence, apologized to Wyden for erroneously saying the NSA did "not wittingly" collect data on millions of Americans. While not naming names, Wyden alluded to a comment made by Alexander last year in which the director of the NSA said publicly: "We don't hold data on US citizens."

"When did it become all right for government officials' public statements and private statements to differ so fundamentally?" Wyden said in his speech.

"The answer is that it is not all right, and it is indicative of a much larger culture of misinformation that goes beyond the congressional hearing room and into the public conversation writ large."

That culture faces one of its first major legislative challenges as early as Wednesday with the vote on Amash's amendment. There are others: a Senate bill introduced in June and co-signed by Wyden would compel declassification of the rulings of the secret Fisa court that sets broad rules for the NSA and FBI's collection and analysis of phone records and online communications.

Additionally, the NSA itself has indicated its willingness to consider abandoning the phone-records collection provided the telecommunications companies it partners with retains the data. And a former judge on the Fisa court wrote an op-ed for the New York Times advocating the secret surveillance court adopt an adversarial process, with a lawyer appointed to "to challenge the government when an application for a FISA order raises new legal issues."

"The side of transparency and openness," Wyden said, "is starting to put some points on the board."