WASHINGTON — Secretary of State Mike Pompeo on Tuesday abruptly canceled a briefing for senators scheduled for Wednesday about the deal with North Korea that President Donald Trump has hailed as a breakthrough — even while the details of the agreement remain vague.

Senate leaders informed colleagues that the briefing may be rescheduled for next week, though no date had been set, according to aides involved in the scheduling.

Pompeo has also not yet committed to a briefing before the Senate Foreign Relations Committee, the committee with jurisdiction over any deal.

“We’ve been going back and forth about the date and subject matter and so forth. Hopefully he’ll be here soon," Sen. Bob Corker, R-Tenn., the committee's chairman, told NBC. “It’s always difficult to schedule a secretary of state."

The aides all spoke on condition of anonymity because they were not authorized to speak on the record. A spokesman for Senate Majority Leader Mitch McConnell, R-Ky., said the leader does not comment on private, all-Senate briefings.

A State Department spokesperson said they did not cancel the meeting, maintaining that a "mutually agreeable time" was not found for the briefing. "We are seeking to schedule a briefing," the spokesperson said. "In the meantime, the secretary is in regular contact with Congress. He looks forward to continuing these engagements and keeping members informed."

Expectations are high that Congress will play a major role and there are many questions on Capitol Hill about what was agreed to.

After Trump became the first sitting U.S. president to meet face-to-face with a North Korean leader, Kim Jong Un, in Singapore this month, several members of Congress demanded that Pompeo brief Congress on the details of any agreement. Trump has boasted on Twitter since that meeting that there is “no longer a Nuclear Threat” from North Korea, even though U.S. intelligence has determined that the country is well on its way to developing nuclear weapons and has tested ballistic missiles capable of delivering heavy nuclear warheads to the U.S.

At least one Republican lawmaker on Tuesday echoed Trump’s assurances.

“The president’s taken us back from the brink of war” as a result of “a successful summit” with North Korea, Sen. John Barrasso of Wyoming, told reporters.

In a Senate Foreign Relations Committee hearing prior to the Singapore summit, Pompeo vowed that Congress would handle North Korea differently. Specifically, he said: “It is absolutely the case that it is our intention to achieve an agreement that would be put before the United States Senate.”

Senate Democratic aides said the briefing's cancellation was cause for concern.

“If this is such a great landmark deal, it’s troubling they don’t want to come and tell us about it,” said one aide. Another was more skeptical: “Unless they (Republican leadership) drag him down here, he’s not going to come.”

Trump and Kim signed a joint statement at the summit agreeing to the eventual “complete denuclearization” of the Korean Peninsula. But the statement did not include critical commitments the U.S. has insisted upon in the past, including that North Korea commit to “verifiable and irreversible” denuclearization. The agreement also included no timeline of specific actions.

By contrast, Trump agreed to several specific concessions, including a pause in joint U.S.-South Korea military exercises. A planned joint drill by the two countries in August has been canceled.