Coincidences do happen, but this seems to be an unlikely one. On Sunday morning, seemingly apropos of nothing, Donald Trump posted a message on Twitter that stated the following: “As only one of two people left who could become President, why wouldn’t the FBI or Department of ‘Justice’ have told me that they were secretly investigating Paul Manafort (on charges that were 10 years old and had been previously dropped) during my campaign? Should have told me!”

Even by Trump’s standards, this message seemed a bit weird. A few minutes later, the President posted another one, which said, “Paul Manafort came into the campaign very late and was with us for a short period of time (he represented Ronald Reagan, Bob Dole & many others over the years), but we should have been told that Comey and the boys were doing a number on him, and he wouldn’t have been hired!”

Trump says a lot of things on Twitter, of course. But prior to this outburst, he hadn’t talked much recently about Manafort, who made millions of dollars working as a political consultant for despots around the world and is facing trial in two federal courts on charges that include money laundering, bank fraud, and failing to disclose his U.S. lobbying work for a foreign government—all of which were brought by the special counsel, Robert Mueller. Why Trump’s sudden interest? One possible inference was that the President had somehow heard that there was more bad news coming about Manafort, and he was trying to limit some of the damage in advance of its release. If that was indeed the case, we now know the source of Trump’s concern.

In a filing made in U.S. district court, in Washington, on Monday night, Mueller’s office accused Manafort, who is out on bail, of trying to tamper with potential witnesses earlier this year, and asked a judge to consider jailing him before his trial. At this stage, obviously, we don’t know how the court will rule. But Manafort is already facing considerable pressure to coöperate with the special counsel’s investigation. If the court were to revoke his freedom, this pressure would sharply increase.

The initial charges filed against Manafort relate primarily to political-consulting work he did for a pro-Russia politician and a pro-Russia political party in Ukraine. The special counsel’s office also claims that Manafort secretly arranged for a group of former European officials, known as the Hapsburg group, to lobby inside the United States on his clients’ behalf, and that Manafort didn’t disclose this activity on federal disclosure forms.

The court filing alleges that, beginning on February 24th, Manafort and a longtime associate—referred to as “Person A”—contacted two public-relations executives—referred to as “Person D1” and “Person D2”—and asked them to pass a message to the members of the Hapsburg group which stated that they never did any lobbying in the United States. One text message, which Person A sent to Person D1, on February 28th, said, “Basically P wants to give him a quick summary that he says to everybody (which is true) that our friends never lobbied in the U.S., and the purpose of the program was E.U.”

The court filing states that Manafort was trying to get the witness to lie on his behalf: “Person D1 has told the government that he understood Manafort’s outreach to be an effort to ‘suborn perjury,’ because person D1 knew that the Hapsburg group worked in the United States—not just Europe.” The filing also says, “Persons D1 and D2 both preserved the messages they received from Manafort and Person A”—Manafort's longtime associate—“which were sent on encrypted applications, and have provided them to the government.”

Assuming that the information in the new filing is accurate, Manafort’s actions seem brazen or desperate, or perhaps both. On Monday night, reporters identified Person A as Konstantin Kilimnik, a Ukrainian with Russian citizenship, who once worked for Manafort’s consulting firm. In a previous court filing, Mueller’s team said that Kilimnik has been “assessed” to have ties to Russian intelligence, an allegation that Kilimnik has denied. His name came up last year, when Mueller’s team claimed he helped edit an op-ed for a Kiev newspaper in coöperation with Manafort. The special counsel said that this op-ed violated a gag order that had been placed on Manafort.

Even before this latest charge, Manafort’s predicament was a very serious one. If he is convicted on all of the charges brought against him, he could face many years in jail. Earlier this year, Manafort’s lawyers challenged Mueller’s legal authority to bring the charges, on the grounds that they were not directly related to the 2016 election. At the end of April, a federal judge tossed out this argument, leaving Manafort to face the prospect of a trial in Virginia next month, followed by another one, in Washington, D.C., in September.

Last December, a judge released Manafort from house arrest on bail of ten million dollars, allowing him to travel to and from Florida, where he has a home, and Washington, where his lawyers are located. Even if the circuit court in D.C. doesn’t send Manafort to jail now for witness tampering, the prosecutors at his trial and possible sentencing will be able to bring up the contacts he had. On Monday night, Manafort’s lawyer didn’t make a comment about Mueller’s new court filing. Neither did Trump—but he didn’t need to. He had already tried to run as far as possible from his former campaign chairman. Now, like everyone else, he will watch what happens next in court, and see if Manafort becomes a coöperating witness.