Democrats are sounding the alarm over a mysterious whistleblower report to the inspector general of the intelligence community that the Trump administration is refusing to provide to Congress.

The complaint involves President Trump's communication with a foreign leader, as the Washington Post first reported Wednesday night and CBS News has confirmed. The identity of that foreign leader and the exact nature of that communication remain unclear, but the Washington Post reported the discussion entailed a "promise."

The New York Times reported on Thursday that the complaint was "related to a series of actions that goes beyond any single discussion with a foreign leader."

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Nearly a week after the dispute spilled into public view, there's still plenty that lawmakers — and the public — don't know yet. Here's what we do know.

Why hasn't Congress seen the report?

The unidentified whistleblower filed the complaint with the intelligence community inspector general, Michael Atkinson, on August 12. Federal law stipulates that the inspector general must investigate any report of an "urgent concern" by an employee of the intelligence community and determine whether it "appears credible" within two weeks. If it is, the inspector general must then report it to the director of national intelligence, whose office is responsible for overseeing the nation's 17 intelligence agencies.

The inspector general investigated the complaint and deemed it credible, forwarding it to the acting director as required, according to a letter from the inspector general released by House Intelligence Committee Chairman Adam Schiff.

Once the director receives the report, the law states he or she "shall, within 7 calendar days of such receipt, forward such transmittal to the congressional intelligence committees."

But Acting Director of National Intelligence Joseph Maguire has refused to share the complaint with Congress. The general counsel for Maguire's office said it had consulted with the Justice Department and determined the complaint did not rise to the level of an "urgent concern" requiring congressional notification. The relevant federal statute defines "urgent concern" as "a serious or flagrant problem, abuse, violation of law or Executive order, or deficiency" related to an "intelligence activity."

"The complaint forwarded to the [inspector general] does not meet the definition of 'urgent concern,'" general counsel Jason Klitenic wrote in a letter to Schiff on Tuesday. "This complaint ... concerned conduct by someone outside the Intelligence Community and did not relate to any 'intelligence activity' under the DNI's supervision."

The committee only became aware of the whistleblower complaint when the inspector general wrote to Schiff on September 9 to inform him of Maguire's decision not to provide it to Congress.

Schiff demanded the acting director provide the complaint and publicly revealed its existence in a letter to Maguire last week. He spoke with reporters after a closed-door briefing with Atkinson on Thursday and suggested the ability for whistleblowers to come forward is being stifled.

House Intelligence Committee Chairman Adam Schiff speaks to reporters at the Capitol in Washington on Thursday, September 19, 2019. J. Scott Applewhite / AP

"That whole purpose is being frustrated here because the director of national intelligence has made the unprecedented decision not to share the complaint with Congress," Schiff told reporters Thursday. "We were informed of this fact after the seven-day period, in which the director has to review it and submit it to Congress, had expired. No complaint was provided and the inspector general felt it necessary to inform the Congress that that complaint was being withheld. In the absence of the actions — and I want to thank the inspector general — in the absence of his actions in coming to our Committee, we might have never known there was a whistleblower complaint alleging an urgent concern."

Which foreign leaders has the president spoken with recently?

In the six weeks leading up to August 12, when the report was filed with the inspector general, Mr. Trump spoke with a number of world leaders.

Those world leaders include, among others, Russian President Vladimir Putin, Saudi Crown Prince Mohammad bin Salman, Chinese President Xi Jinping, North Korean leader Kim Jong Un, Pakistani Prime Minister Imran Khan and Ukrainian President Volodymyr Zelensky.

What has Trump said about the complaint?

The president is defending himself by insisting he speaks with world leaders often and assumes others might be listening, blasting the "fake news" media over coverage of the complaint.

"Another Fake News story out there - It never ends!" the president tweeted Thursday morning. "Virtually anytime I speak on the phone to a foreign leader, I understand that there may be many people listening from various U.S. agencies, not to mention those from the other country itself. No problem! ...Knowing all of this, is anybody dumb enough to believe that I would say something inappropriate with a foreign leader while on such a potentially 'heavily populated' call. I would only do what is right anyway, and only do good for the USA!"

What's next?

Atkinson briefed lawmakers behind closed doors on Thursday, and Maguire is expected to testify in open session before the House Intelligence Committee next week after testimony this week was delayed. The Senate Intelligence Committee expects to be briefed by both about the complaint next week, according to a committee spokesperson.

Olivia Gazis contributed reporting.