President Trump is moving to revive the watchdog agency that oversees major surveillance programs, but some privacy advocates see his pick to lead it as overly deferential to the intelligence community.

Adam Klein, announced Friday as Trump's pick for chairman of the Privacy and Civil Liberties Oversight Board, has taken sides in one of the biggest policy debates this year: whether authorities need a warrant to search American communications collected "incidentally" under Section 702 of the Foreign Intelligence Surveillance Act, which expires this year unless Congress acts.

Klein, a former Antonin Scalia clerk who works at the Center for a New American Security, opposes a warrant rule, writing in a Wall Street Journal op-ed last month that "keeping officials from searching this data would make it more difficult to prevent homegrown terrorist attacks."

Klein pointed to the contested example of Najibullah Zazi, who was arrested in 2009 for plotting to bomb New York's subway system.

"He's extremely deferential to the intelligence community, almost to the point where he fails to ask the tough questions," said Robyn Greene, policy counsel and government affairs lead at the New America Foundation's Open Technology Institute.

"The warrantless query of U.S. person information is a perfect example," she said. "It's very important as the chair of the Privacy and Civil Liberties Oversight Board that you be really scrupulous about addressing the concerns of the privacy community as well as the arguments of the intelligence community."

Section 702 of FISA allows authorities to collect communications of foreigners that transit U.S. internet infrastructure, but sometimes wholly domestic communications are taken and loaded into searchable databases. Opponents say looking at those records for information on Americans is a "backdoor search" that violates the Fourth Amendment.

"It's an unfortunate situation that the head of the government's civil liberties watchdog panel [would be] on record opposing the reforms that the civil liberties community uniformly supports," said Elizabeth Goitein, co-director of the Brennan Center for Justice's Liberty and National Security Program.

"He's been very public and very detailed about what he thinks needs to happen with 702," she said. "There will be no surprises. The administration knows what it's getting. And what it's getting is someone who opposes any significant substantive reform."

Goitein added: "at the same time, he does support some tweaks to the law. And those tweaks won't get at the main issues, but they will make it a lot harder to dismiss him as an apologist for the status quo. And he's a smart, thoughtful guy."

Klein, who did not respond to a request for comment, wrote in a March report that searches of Section 702 records "raise legitimate privacy concerns — particularly if such information flows downstream into the criminal justice system" and recommended more transparency, as "relatively little public information is available about these queries: their frequency, how often they return 702 information, and precisely why the FBI views them as valuable."

PCLOB in its current form was established by 2007 legislation. It wasn't fully functional until 2013 and took a major role reviewing programs exposed that year by NSA contractor Edward Snowden. Its report on the mass-collection of domestic call records played a role in the legislated demise of that program and the board authored a lengthy report on Section 702 internet surveillance programs.

It's unclear what explains the Trump administration's timing in moving to revive the five-member board, which has been unable to hire staff since its last chairman resigned in July 2016 and which has lacked a three-person quorum required for official actions since January.

One potential explanation for the timing is the looming debate over renewing Section 702. Another is the fact that the European Commission is preparing for a September review of the economically significant 2016 Privacy Shield deal with the U.S., which govern how American companies handle the data of Europeans. The agreement identifies the board as a designated review body for complaints referred by a Privacy Shield ombudsman. Privacy critics, particularly in Europe, where a court ruling killed an earlier agreement, question the adequacy of safeguards.

Despite their qualms, Greene and Goitein doubt the Senate would block Klein's nomination. And some privacy advocates are withholding public judgment.

"We look forward to working with Mr. Klein, and hope that this will be the first step in fully reconstituting the board," said Michelle Richardson, a deputy director of the Center for Democracy and Technology, which supports a warrant requirement for "backdoor" searches.

"While best known for its work on FISA, the PCLOB has jurisdiction over counterterrorism programs generally, and and we encourage it to evaluate and disclose more information about additional collection programs," she said.

Sen. Ron Wyden, the Oregon Democrat and Senate intelligence committee member who often takes a leadership role on privacy issues, has not developed a position. "Our office is just starting to review Mr. Klein's nomination," said spokesman Keith Chu.

Coming from the other side of the debate, Susan Hennessey, a former National Security Agency attorney who works at the Brookings Institution, pushed back on concern about Klein, saying that his positions "strike me as rather moderate on this topic."

"The PCLOB is structured to ensure both ideological and political diversity, so it is natural and healthy that the ultimate make-up of the board will reflect a range of views on a controversial subject," she said. "The FBI has repeatedly made the case for why measures like a post-collection warrant requirement would impede their ability to operate to counter threats. Adam has proposed meaningful 702 reforms aimed to increase privacy and transparency, without harming overall security."

Elisebeth Collins, a Republican attorney and currently the only PCLOB member, meanwhile, said she was pleased with Klein's nomination.

"Adam is an accomplished and well-respected national security and intelligence expert with a deep understanding of issues related to counterterrorism," she said. "I know him to be committed to the mission of the Privacy and Civil Liberties Oversight Board: to ensure that efforts by the executive branch to protect the nation from terrorism are balanced with the need to protect privacy and civil liberties."

A White House spokeswoman declined to comment on when there will be nominations for the remaining three PCLOB vacancies. Two of the spots are reserved for Democrats and are expected to be filled by names offered by Senate Minority Leader Chuck Schumer. A member of Schumer's staff did not immediately respond to a request for comment, but some privacy advocates are pushing for Alvaro Bedoya, executive director of the Center on Privacy and Technology at Georgetown University's law school.

It's unclear what's ahead for the Section 702 legislative debate. Bipartisan majorities in the House of Representatives voted in 2014 and 2015 to require a warrant for incidentally collected records, but the Senate did not act and the House defeated a warrant rule last year shortly after the Orlando nightclub shooting.