A senior member of the Senate Intelligence Committee is vowing to block a vote to confirm President Joe Biden’s pick to helm U.S. Cyber Command and National Security Agency until he receives more details about a controversial surveillance practice.

Sen. Ron Wyden (D-OR) pledged Thursday to object to Air Force Lt. Gen. Timothy Haugh receiving a floor vote until the Defense Department acknowledges if the spy agency he has been picked to lead is buying the location data and web browsing records of U.S. citizens from data brokers.

“The American people have a right to know whether the NSA is conducting warrantless domestic surveillance of Americans in a manner that circumvents the Fourth Amendment to the Constitution,” Wyden said in a statement put in the Congressional Record.

Haugh’s nomination was sent to the full chamber in July and already has been stymied, along with the nominations of hundreds of other military officers, in the nearly yearlong blockade by Sen. Tommy Tuberville. The Alabama Republican, however, has indicated he could lift his blanket hold as soon as next week

For now, Haugh remains deputy chief of Cyber Command.

Wyden’s move comes as congressional leaders are trying to chart a path forward on the renewal of a major foreign spying tool: Section 702 of the Foreign Intelligence Surveillance Act (FISA). A short-term extension of the program, which will expire at the end of the calendar year, is expected to be hitched to the annual defense policy bill to give lawmakers more time. That measure will be released next week.

Wyden is a lead sponsor of a reform-minded FISA renewal bill that incorporates previous legislation that would close loopholes that allow data brokers to sell consumer data to law enforcement and federal agencies.

In his statement, the longtime privacy hawk noted that in 2021 he made public an unclassified memo from the Defense Intelligence Agency that showed the Pentagon’s spy arming was purchasing location data of American citizens.

He rattled off a series of exchanges with DoD officials since, which led to him to “regretfully” object to Haugh’s promotion.

A defense official said the department is “aware” of Wyden’s hold.

“The Department looks forward to working with Senator Wyden to address his concerns. This position plays a critical role in keeping our country safe, and we look forward to working with the Senate to confirm LTG Haugh, someone with deep experience and knowledge of cyber security, as soon as possible,” the official said in a statement.