WASHINGTON – Like its predecessor, the Obama administration says it cannot count how many people in the U.S. have had their telephone calls and emails monitored by government agents in national security investigations under federal surveillance law.

The national intelligence office said in a letter this week to two Senate Democrats that it was “not reasonably possible to identify the number.”

The senators, Ron Wyden of Oregon and Mark Udall of Colorado, worry that the government may be monitoring communications of law-abiding citizens with inadequate justification.

“We’re not asking these questions to embarrass the administration or make the intelligence community’s job more difficult,” Wyden said in a statement Thursday. “Congress needs to know if the laws it writes are being…implemented as intended.”

The letter from the office of James Clapper, director of national intelligence, was a response to the senators’ requests for information about how the Obama administration is interpreting amendments in 2008 to the Foreign Intelligence Surveillance Act.

The 2008 FISA amendments allow the government to obtain from a secret court broad, yearlong intercept orders that target foreign groups, raising the prospect that phone calls and e-mails between those foreign targets and innocent Americans in this country will be swept in.

In saying it was unable to provide a number, the administration’s letter pointed Wyden and Udall to classified reports provided to Congress that give the number of circulated intelligence reports that refer to at least one person in the United States and give the number of collection targets later determined to be in the United States.