Donald Trump’s national security adviser, Michael Flynn, may be in a lot of trouble.

Late Thursday night, the Washington Post reported that Flynn had called Russian Ambassador Sergey Kislyak on December 29, the same day that Obama had slapped new sanctions on Russia in retaliation for its hack of the US election. The conversation covered the sanctions, and, according to two officials, suggested that the Trump administration would be rolling back the sanctions in the future.

That would mean Flynn had been actively trying to undermine Obama administration policy while not yet in office — a big, questionably legal no-no. Indeed, the FBI is currently investigating the content of the Flynn calls.

The Trump administration repeatedly and publicly denied that Flynn had spoken to Kislyak about sanctions, even enlisting Vice President Mike Pence to back him up in the media. Flynn himself told the Post on Wednesday that he hadn’t talked about sanctions. But the Post spoke to nine former and current US officials with knowledge of the call, which was actually recorded by US intelligence agencies (as all such high-level calls to the Russian ambassador are). Subsequent reporting from other outlets backed the Post up.

On Thursday, Flynn, through his spokesperson, backed away from the denial. The spokesperson said Flynn “indicated that while he had no recollection of discussing sanctions, he couldn’t be certain that the topic never came up.”

All of which means that it’s very likely that Flynn lied about the content of his talks with the Russian ambassador. That leaves two big outstanding questions:

Did Flynn lie to Pence about sanctions, or did Pence knowingly lie to the American public? Did Flynn lie to FBI investigators, too?

The answers could help determine whether Flynn keeps his job — and, potentially, whether he faces criminal charges.

Why the new report is such a problem

Questions about Flynn’s relationship with Russia go all the way back to the campaign, where he served as one of Trump’s top national security staffers. Flynn has spoken very positively about the prospect of partnering with Putin’s regime to fight terrorism, and repeatedly appeared on Russia’s English-language propaganda outlet, RT. Flynn was so in with RT that he had been paid to give a speech at its 10th anniversary dinner in Moscow — where he sat at the head table with Putin himself.

So when Obama imposed sanctions on Russia in retaliation for the election hack, the widespread expectation was that Flynn would work to roll them back once in office. But attempting to undermine them before taking power — on literally the day they were imposed — was something else. It could, arguably, violate the Logan Act, a law which prohibits people outside the executive branch from making foreign policy on behalf of the US administration (though no one has ever been prosecuted under this act).

The first public report of the call came on January 12, in a column by the Washington Post’s David Ignatius. Follow-ups came swiftly, with administration sources saying the two men had spoken multiple times on the 29th but that they hadn’t discussed sanctions.

That rang hollow to many close observers of the Kremlin, who noted that just one day later Putin announced that he would not retaliate against the US for the sanctions. That was a sharp break with Putin’s normal policy of hitting back hard for any slight, real or perceived. It makes a lot more sense if Putin had just gotten assurances from the next national security adviser that the sanctions would soon go away.

The Trump administration denied that the call was about the sanctions. Trump spokesperson Sean Spicer told reporters that call had grown out of an exchange of holiday greetings on December 25 — a questionable story given that this year’s Russian Orthodox Christmas was actually on January 9, 2017.

On January 15, the White House rolled out a heavyweight: Vice President Pence went on Fox and CBS’ widely watched Sunday talk shows to sell the Christmas-not-sanctions story.

“It was initiated when on Christmas Day, he had sent a text to the Russian ambassador to express not only Christmas wishes but sympathy for the loss of life in [a Russian] airline crash that took place” at the time, Pence said during a January 15 appearance on CBS’s Face the Nation. “It was strictly coincidental that they had a conversation, they did not discuss anything having to do with the United States’ decision to expel diplomats or impose censure against Russia.”

The general outlines of the administration’s story meandered and wavered in some weird ways, as Just Security’s Kate Brannen documents in depth. But one on issue, the Trump team had maintained a clear line: Flynn had not spoken about sanctions with Kislyak on December 29.

He might want to start polishing his resume

Initially, this seemed tenable. On January 23, the Washington Post (which clearly owns this story) reported that the FBI counterintelligence agents had been investigating Flynn’s phone calls in late December but hadn’t found any evidence of illegal contact with Russia after an initial scan of the calls.

“The FBI in late December reviewed intercepts of communications between the Russian ambassador to the United States and retired Lt. Gen. Michael T. Flynn — national security adviser to then-President-elect Trump — but has not found any evidence of wrongdoing or illicit ties to the Russian government,” the Post explained.

It looked like Phonecallgate might die.

The new Post report, though, does more than simply bring the story back to life. It goes even further, using a large number of sources to paint a picture of an administration where the national security adviser either knowingly lied to the vice president about the content of his conversations with Kislyak (leading Pence to unintentionally relay false information to the American public) or one in which Pence himself deliberately lied.

“All [nine] officials said ­Flynn’s references to the election-related sanctions were explicit,” the Post’s Greg Miller, Adam Entous and Ellen Nakashima write. “Two of those officials went further, saying that Flynn urged Russia not to overreact to the penalties being imposed by President Barack Obama, making clear that the two sides would be in position to review the matter after Trump was sworn in as president.”

The quality and quantity of the sourcing was so persuasive that even Flynn, who stuck to the old Trump line when the Post reporters first contacted him, eventually had to back down. Moreover, the Post reported, the FBI counterintelligence probe into Flynn’s call is still active.

While the FBI was very unlikely to prosecute Flynn under the Logan Act, lying to FBI investigators is a whole different kettle of fish. If FBI agents had asked him, specifically, about the content of the calls, and he denied speaking to Kislyak about sanctions in the way he had publicly, then he could be (to use a technical legal phrase) in big trouble.

Pence isn’t waiting for the FBI to finish its investigation to seemingly throw Flynn under the bus. Three administration sources told CNN’s Elizabeth Landers on Friday that Flynn had not informed Pence that he had spoken about sanctions when he appeared on TV. “It’s a problem,” one of Landers’ sources said.

This is exactly what one would do if one was getting ready to fire Flynn — to pin this mess on him entirely as a way of immunizing the broader administration from the charge of deceiving the American people. Reportedly, Flynn was already in trouble with the Trump team, on both personal and professional grounds, even before this started.

Flynn “has gotten on the nerves of Mr. Trump and other administration officials because of his sometimes overbearing demeanor,” the New York Times’ Maggie Haberman and Glenn Thrush write. He “has further diminished his internal standing by presiding over a chaotic and opaque NSC transition process that prioritized the hiring of military officials over civilian experts recommended to him by his own team.”

Does this mean Flynn will be fired? No, absolutely not. Flynn is a longtime Trump partisan, and Trump values loyalty greatly.

It does, though, mean that he might want to start polishing his resume. As Chris Christie learned during the transition, Trump is perfectly happy to toss a loyalist to the wolves if they get ensnared in a scandal that shows little sign of going away. And that’s exactly where Flynn is now.