WASHINGTON — Biden administration officials urged Congress on Tuesday to renew a surveillance program that the U.S. government has long seen as vital in countering overseas terrorism, cyberattacks and espionage operations.

The program, which is under the Foreign Intelligence Surveillance Act, or FISA, grants American spy agencies sweeping powers to surveil and examine communications of foreigners located outside the United States. It's set to expire at year's end unless Congress agrees to renew it. Officials in the Democratic administration are bracing for a contentious debate on Capitol Hill about reauthorizing the program, with civil liberties advocates aligning with Republicans in raising concerns about the scope of the government's spy powers.

In an effort to preemptively head off privacy concerns, intelligence and national security officials sought to make a public case Tuesday that the statutory authorities at risk of expiring have yielded valuable insight in recent years into ransomware attacks on critical infrastructure, disrupted efforts to recruit spies and contributed to the killing of al-Qaida leader Ayman al-Zawahri in a drone strike last August.

At issue is a provision of FISA known as Section 702 , which allows spy agencies to collect huge swaths of foreign communications. But that tool has drawn scrutiny from civil liberties advocates because it results in the incidental collection from Americans when those Americans are in contact with the foreign surveillance targets.

Section 702 was first added to FISA in 2008 and was renewed for six years in 2018, when then-President Donald Trump, who routinely lambasted government intelligence agencies, originally tweeted opposition to the program but then reversed himself.

This year's fight for renewal is again unfolding in a polarized political climate, as Republicans still angry over FBI errors made during the investigation into links between Russia and Trump's 2016 presidential campaign have cast themselves as skeptical over the government's need for broad spy powers and maintain that the authorities are ripe for abuse and overreach.

As part of an effort to persuade Congress to renew the program, and to present themselves as willing to make any needed adjustments to safeguard against abuses, the administration released a letter to lawmakers from Attorney General Merrick Garland and Avril Haines, the national intelligence director.

Separately, Assistant Attorney General Matthew Olsen, the Justice Department's top national security official, delivered the same message in a speech at the Brookings Institution think tank.

“The bottom line is that Section 702 gives us the intelligence necessary to stay one step ahead of our adversaries,” Olsen was to say, according to a copy of his prepared remarks. “We cannot afford to allow it to lapse. And it is too important to the interests of the U.S. and our allies — and to our basic safety — to wait for the 11th hour to do so.”

National security officials say Section 702 makes possible their most critical work, from collecting intelligence on China to stopping ransomware attacks and other cyber intrusions that have disrupted government agencies and a wide range of industries. But they have declined to publicly give specifics of how they use surveillance programs, saying those are classified.

Courts and lawmakers have gotten a more detailed look at the program, but in private. Intelligence leaders have already been speaking to key lawmakers about Section 702 and will give classified and unclassified briefings to Congress later this year.

In their letter to Congress, Garland and Haines note that every court to consider Section 702’s bulk data program “has found it to be constitutional.”

The intelligence community has also never released a precise figure on how many searches are conducted of their bulk data for information on Americans. In its most recent transparency report, the Office of the Director of National Intelligence said the FBI had conducted “fewer than 3,394,053” searches during 2021.

Besides civil liberties concerns, there are also questions about whether power given to U.S. intelligence after the Sept. 11, 2001, terror attacks should be extended as it broadly refocuses from counterterrorism to what’s often called “great power competition” — Washington’s rivalries with Beijing and Moscow — and a range of other threats including cyberattacks.