National Security Agency officials are collecting more information on foreigners' communications than ever before, a top spy official told lawmakers.

"The amount of total collection has increased generally every year," NSA director Mike Rogers told the Senate Intelligence Committee on Wednesday. "It's more and more impactful for us. It generates more and more value."

The law authorizing such data collection, known as Section 702, has been among the most controversial of the intelligence community's surveillance powers for years. Privacy advocates have long worried that the government would abuse the authority, while national security hawks maintain that it provides crucial intelligence. The program will expire this year without a new stamp of congressional approval.

Rogers and other intelligence officials appeared before the committee to lobby for the reauthorization of the program. "Section 702 is a critical foreign intelligence tool that the Intelligence Community uses properly to target non-U.S. persons located outside the United States to acquire information vital to our national security," Dan Coats, director of National Intelligence, told the Senate panel in his prepared testimony

That has been a widespread view on Capitol Hill, but the political uproar over President Trump and his team's reported contacts with Russian officials has created new hesitation about the program. Republican lawmakers who typically give full-throated support for the program worry that political opponents of the Trump administration in government are abusing their access to information collected by the program.

"I'm not going to reauthorize a program that could be politically manipulated," Sen. Lindsey Graham, R-S.C., said Tuesday.

Trump's team supports a proposal to give the program a permanent reauthorization. "Simply put, the use of this authority has helped save lives," Thomas Bossert, a counterterrorism adviser to Trump, wrote in the New York Times.

Sen. Tom Cotton, R-Ark., who introduced legislation reauthorizing the program, asked Rogers to describe his support for the bill. "I would be ecstatic that we'd be in a position to continue to generate significant insights for this nation's security," Rogers said.