Efforts to renew the spying power, known as Section 702 of the FISA Act, face resistance from both parties before its slated expiration date at the end of the year. Lieutenant general Timothy Haugh, Biden’s pick to replace outgoing NSA leader general Paul Nakasone, defended it yesterday as a critical authority that had enabled the intelligence community to gather information on a host of threats.

“In my experience it is absolutely essential,” he told lawmakers.

The programme – which came under widespread scrutiny following the disclosures of former intelligence contractor Edward Snowden a decade ago – is typically framed by its defenders as sweeping up information on non-Americans living outside the US.

That is how Haugh described it during his confirmation hearing before the Senate Intelligence Committee, saying he wanted to ensure that “American people understand that this is an authority to collect against foreign persons overseas.”

That is not the full story, however.

A substantial chunk of the data swept up by the NSA’s mass surveillance apparatus belongs to Americans living in the US. In theory, exploiting this warrantlessly collected data is subject to certain safeguards. But the recent disclosure that the FBI improperly combed through the database more than a quarter million times over several years has only heightened concerns from civil libertarians and lawmakers about Section 702’s potential for abuse.

Haugh is unlikely to face too much resistance from the Senate Intelligence Committee on the matter, however.

“We desperately need to get 702 reauthorised,” Committee chairman Mark Warner told him as he kicked off his testimony.