Adam Klein’s nomination to lead the largely dormant Privacy and Civil Liberties Oversight Board goes before the Senate Judiciary Committee on Wednesday, but some supporters of the board’s mission aren’t thrilled about the idea of Klein leading the body’s revival.

Klein, a former Antonin Scalia clerk who works at the Center for a New American Security, opposes a warrant rule for domestic communications intercepted under Section 702 of the Foreign Intelligence Surveillance Act, a contentious policy position.

Klein’s stance on U.S. communications collected from the Internet’s backbone under that law puts him in line with a majority of House and Senate members, who defeated reform efforts this month, but upsets policy advocates who view the searches as unconstitutional.

“In terms of Klein's background, it is concerning that he has previously taken a strong stand against reforms to NSA authorities that are absolutely necessary,” said Neema Singh Guliani, legislative counsel at the American Civil Liberties Union.

Guliani said she’s also concerned that if Klein were confirmed there would be two Republicans and no Democrats on the five-person PCLOB, which took a leading role investigating and publicizing details about government surveillance programs after NSA contractor Edward Snowden’s 2013 leaks to the media.

“Congress should press Klein and other nominees to commit to work to improve transparency,” she said. “Specifically, the public and members of Congress have asked the intelligence agencies to provide an estimate of the number of individuals in the U.S. who have their information collected under Section 702.”

Guliani also would like to see Klein commit to reviewing the disparate impact of surveillance on different communities.

Robyn Green, policy counsel and government affairs lead at the New America Foundation's Open Technology Institute, said upon Klein’s nomination in August that “he's extremely deferential to the intelligence community, almost to the point where he fails to ask the tough questions.”

Ahead of the confirmation hearing, Green expressed hope that “if he becomes chair of the PCLOB, he will recognize the importance of including the perspective of privacy advocates, and since he does not have a strong background in privacy and civil liberties issues, he will ensure that he hires staff who can fill that gap.”

Klein wrote in a Wall Street Journal op-ed in July about his support for continued warrantless access to domestic communications taken under Section 702 of FISA, arguing 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.

“Some members of Congress now propose to erect new barriers against information-sharing within the intelligence community that could make it even more difficult for officials to spot future terrorists before they strike,” Klein wrote.

Elizabeth Goitein, co-director of the Brennan Center for Justice's Liberty and National Security Program, said in August that “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.”

"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 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 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.

The board has been unable to hire staff since its last chairman resigned in July 2016 and has lacked a three-person quorum for official actions since January.

Although a key institutional watchdog following Snowden’s revelation, the PCLOB also holds an important role under the economically significant 2016 Privacy Shield deal between the European Union and 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.

The chances of Klein’s nomination being derailed currently appear slim.

Susan Hennessey, a former National Security Agency attorney who works at the Brookings Institution, pushed back on concerns about Klein, telling the Washington Examiner in August 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, all but endorsed his nomination, saying shortly after he was selected: "Adam is an accomplished and well-respected national security and intelligence expert with a deep understanding of issues related to counterterrorism. 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."

It’s unclear when the White House intends to nominate people to fill 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, D-N.Y. 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.