WASHINGTON — Two senior U.S. officials told NBC News on Monday that the FBI is prepared to brief congressional leaders on the counterintelligence findings of special counsel Robert Mueller's investigation.

The FBI opened a counterintelligence investigation into President Donald Trump, and the letter sent to Congress on Sunday by Attorney General William Barr about the Mueller probe is silent on the question of whether investigators found that Trump or anyone around him might be compromised or influenced by Russia.

The officials said they expect the FBI to brief the so-called Gang of 8 — the leaders of the House and the Senate and the chairmen and ranking members of the intelligence committees — in closed session.

No briefing has been scheduled, a third U.S. official familiar with the matter said, but one of the officials said it could happen within the next 30 to 60 days.

Congressional Democrats have demanded such a briefing under a law requiring the executive branch to keep Congress informed about intelligence activities.

Speaker of the House Nancy Pelosi, D-Calif., said during a conference call with House Democrats on Saturday she would reject any classified briefings, but the Senate Intelligence Committee wants one, according to Senate aides, to assist in its ongoing Russia investigation.

The House Intelligence Committee said it had postponed testimony by Trump associate Felix Sater that was previously scheduled for Wednesday, and would instead focus on interviewing witnesses about counterintelligence. Sater was expected to discuss his work on a proposed Trump Tower in Moscow.

"In light of the cursory statement from the Attorney General," said Patrick Boland, a spokesperson for committee chair Rep. Adam Schiff, D-Calif., "and our need to understand Special Counsel Mueller's areas of inquiry and evidence his office uncovered, we are working in parallel with other Committees to bring in senior officials from the DOJ, FBI and SCO [the Office of Special Counsel] to ensure that the Committee is fully and currently informed about the SCO's investigation, including all counterintelligence information."