A BIPARTISAN GROUP of lawmakers is none too happy that the executive branch is asking them to reauthorize two key surveillance programs next year without answering the single most important question about them.

The programs, authorized under Section 702 of the Foreign Intelligence Surveillance Act, are called PRISM and Upstream. PRISM collects hundreds of millions of internet communications of “targeted individuals” from providers such as Facebook, Yahoo, and Skype. Upstream takes communications straight from the major U.S. internet backbones run by telecommunications companies such as AT&T and Verizon and harvests data that involves selectors related to foreign targets.

But both programs, though nominally targeted at foreigners overseas, inevitably sweep up massive amounts of data involving innocent Americans.

The question is: How much? The government won’t answer.

Fourteen members of the House Judiciary Committee sent a letter to Director of National Intelligence James R. Clapper on Friday asking for at least a rough estimate.

“In order that we may properly evaluate these programs, we write to ask that you provide us with a public estimate of the number of communications or transactions involving United States persons subject to Section 702 surveillance on an annual basis,” said the letter. Signatories included ranking Democrat John Conyers Jr. and a senior Republican member, James Sensenbrenner.

Sen. Ron Wyden has asked for a number since 2011; the Privacy and Civil Liberties Oversight Board recommended in July 2014 that the government provide several. In October, more than 30 privacy groups asked for an estimate and explained how easy it would be to come up with one.

“House Judiciary Committee members have lent their voices to the growing chorus demanding hard facts about how foreign intelligence surveillance affects Americans,” said Elizabeth Goitein, co-director of the Brennan Center’s Liberty and National Security Program, in a statement. “The NSA will soon be asking Congress to reauthorize the Foreign Intelligence Surveillance Act, and it will repeat its past claims that any collection of Americans’ communications is merely ‘incidental.’”

But, Goitein said, “We still don’t have this basic information.”