“If we don’t take a unique moment in our constitutional history — in our political history — to fix a surveillance system that [is] just off the rails, I think we’ll regret it,” Sen. Ron Wyden (D-Ore.) said. (Charles Dharapak/AP)

It was one of the strangest personal crusades on Capitol Hill: For years, Sen. Ron Wyden said he was worried that intelligence agencies were violating Americans’ privacy.

But he couldn’t say how. That was a secret.

Wyden’s outrage, he said, stemmed from top-secret information he had learned as a member of the Senate Intelligence Committee. But Wyden (D-Ore.) was bound by secrecy rules, unable to reveal what he knew.

Everything but his unhappiness had to be classified. So Wyden stuck to speeches that were dire but vague. And often ignored.

“I want to deliver a warning this afternoon: When the American people find out how their government has secretly interpreted the Patriot Act, they will be stunned and they will be angry,” Wyden said on the Senate floor in May 2011.

Two years later, they found out.

The revelations from former National Security Agency contractor Edward Snowden — detailing vast domestic surveillance programs that vacuumed up data on phone calls, e-mails and other electronic communications — have filled in the details of Wyden’s concerns.

So he was right. But that is not the same as winning.

To change the law and restrict domestic spying, the low-key Wyden still must overcome opposition from the White House and the leaders of both parties in Congress.

“If we don’t take a unique moment in our constitutional history — in our political history — to fix a surveillance system that [is] just off the rails, I think we’ll regret it,” he said in a telephone interview Friday.

Now, in the aftermath of Snowden’s disclosures, Wyden is pressing his case on two fronts.

One uses Congress’s power to ask questions. Wyden has sought to force spy agency leaders to clarify — in public — the nature of their intelligence-gathering on Americans.

On Friday, Director of National Intelligence James R. Clapper Jr. responded to a letter co-authored by Wyden with new details.

Clapper said the government was not using its authority under the Patriot Act to collect bulk data on Americans, beyond two programs already disclosed. One gathers data on phone calls. The other, now shut down, gathered data on electronic messages. Clapper also conceded that there had been “compliance problems,” in which the NSA had not met the terms of secret-court orders that allowed the data-gathering.

In addition, Wyden is seeking legislative change, including an overhaul of the Foreign Intelligence Surveillance Court.

“It’s the most one-sided legal process in the United States,” Wyden said in an interview on C-SPAN’s “Newsmakers” that aired Sunday. “I don’t know of any other legal system or court that really doesn’t highlight anything except one point of view.”

He said later that lawmakers should seek to “diversify some of the thinking on the court.”

‘The right questions’

Wyden, 64, is not possessed of a troublemaker’s personality. He has been an earnest, cordial presence in Congress since 1981. Before that, he got his political education as an activist with the Oregon chapter of a group known as the Panthers — not Black, but Gray. As a 20-something, Wyden was a leader of the Gray Panthers, an activist organization for seniors.

But now, Wyden is a man troublemakers look up to.

“He did lay the groundwork. He asked the right questions at the right times. He made the public aware that there were things going on that they probably would not approve of,” said Rep. Justin Amash (R-Mich.), a libertarian who has defied both parties’ leaders — rarely more so than last week.

Amash, along with Rep. John Conyers Jr. (D-Mich.), sponsored an amendment that would have severely limited the government’s ability to collect Americans’ telephone records. It failed Wednesday in the House by a surprisingly close vote of 217 to 205.

“I have come to admire him very much,” Amash said of Wyden.

So Wyden finally has the audience he sought. All it took was Snowden. This is an awkward fact of Wyden’s success: To get anyone’s attention, the senator needed somebody else to break the laws that he would not.

“This debate should have started long, long, long ago. And it should have been started by elected officials and not by a government contractor,” Wyden said Friday.

He said he spent years trying to start the debate, without actually saying what the debate was about.

This was strange work. Many members of Wyden’s staff did not have security clearances, so even they had trouble figuring out what he was trying to say.

“It’s like Minesweeper,” former Wyden staffer Jennifer Hoelzer told The Washington Post’s Ezra Klein in June, referring to the computer game in which players slowly probe unknown territory, looking for bombs. “You just have to ask questions to try to get the outlines of what they’re not telling you. Because they can’t tell you what they’re not telling you.”

In public, Wyden began a kind of Mad Libs campaign, leaving big blanks for others to fill in. He said a “secret law” had begun to guide U.S. intelligence-gathering. The George W. Bush administration, and then the Obama administration, had privately stretched the powers granted by the Patriot Act far beyond the letter of the law.

But he didn’t say how or how far.

The answer wasn’t learned until Snowden appeared: The government had persuaded a secret court to allow the “bulk collection” of records on Americans’ phone calls.

Instead of targeting just the calls of terrorism suspects, the program records “metadata” for millions of calls between average Americans. This includes the numbers dialed and the duration of calls, but not the content of calls. Intelligence officials have defended this program, saying their ability to connect phone numbers has led them to disrupt dozens of terrorist plots in the United States and overseas.

A separate program collected metadata on e-mail and other online communications. It stopped in 2011; Wyden said he lobbied hard to close it in secret meetings with intelligence officials.

‘Trolling for leaks’

Today, Wyden’s wink-and-nod activism is praised by electronic privacy groups. They said the senator told them where to look for abuses, mentioning specific sections of the law that were being misused.

Others see something less laudatory: a senator who was tip-toeing on the edge of secrecy rules.

“I would characterize what he’s been doing as trolling for leaks. And hinting at the kinds of leaks that he wants to see,” said Stewart A. Baker, a former official at the NSA and the Department of Homeland Security. “He’s directed everybody’s attention — who didn’t sign the oath that he signed — to places where they might look.”

Along the way, Wyden staged several odd confrontations with the administration over what he called errors in public statements. They often amounted to public fights in private code.

In March, for instance, Wyden asked Clapper about domestic ­intelligence-gathering.

“Does the NSA collect any type of data at all on millions or hundreds of millions of Americans?” he asked.

Wyden knew the answer. Clapper knew the answer. The answer was yes.

“No, sir,” Clapper said.

This tactic has been criticized by people close to the intelligence community. Joel F. Brenner, a former NSA senior counsel, called it a “low dishonorable act” in a recent post at the blog Lawfare. Brenner objected to Wyden “putting Clapper in the impossible position of answering a question that he could not address truthfully and fully without breaking his oath not to divulge classified information.”

But Wyden counts it a success and a necessary move (he also says he warned Clapper about the question beforehand). He said he wanted to establish a public marker to show that the administration had been spreading untruths about the reach of domestic spying.

“You can’t do vigorous oversight if the leaders of the intelligence community are misleading the American people, and Congress, in public hearings,” Wyden said.

After Snowden’s leaks, attention focused on Clapper’s false statement. The intelligence chief later said he had struggled with his duty not to disclose classified programs in the hearing. Clapper said he had responded in the “least untruthful manner.” He also apologized to Wyden. The Obama administration has said that it “welcomes” a debate on privacy and national security.

Now, Wyden says he will press — along with allies such as Sen. Mark Udall (D-Colo.) — for legislation to end the bulk collection of telephone records and to declassify some decisions by the secret court. Amash says he will try similar tactics in the House.

There are powerful opponents in both parties. But both men said they feel momentum on their side.

“We’re starting to put some points on the board,” Wyden said, noting the close vote on Amash’s amendment. “There is no question in my mind that our side is going to grow, and we’re going to stay at it until this is fixed.”

Ed O’Keefe and Peter Wallsten contributed to this report.