President Trump’s former attorney Michael Cohen says that Trump repeatedly lied during the campaign when he denied have any deals or anything to do with Russia. Others knew as well, presumably — his daughter and son-in-law who worked on the project, Felix Sater who reached out to the Russian and — this is key — the Russians. If you believe Cohen, then Russians knew Trump was lying and Trump knew that they knew. That’s leverage. Former FBI official Frank Figliuzzi explains:

At any time, Vladimir Putin could use — or perhaps he already has used — knowledge of Trump’s deceit to pressure Trump on everything from sanctions to public statements to policy on Ukraine.

Incoming House Intelligence Committee Chairman Adam Schiff (D-Calif.) recently expressed concern about this exact problem.

Former FBI special agent Clint Watts agrees that Trump handed Putin “a window of opportunity should he choose to use it to discredit President Trump at any time President Trump doesn’t do what President Putin likes.” Watts tells me, “I’m not sure he would employ that compromising knowledge at this point, but he could, maybe when meetings get canceled at the G20 for example and Putin begins to sour on Trump.”

Now leverage may come from other sources as well, says former acting CIA director John McLaughlin. The “seeds of blackmail,” he tells me, come from the ongoing business negotiations also also from “the Trump Tower meeting on June 9, even if nothing came of it.” He says, “If we had never learned of it, Russia would have had in its kit bag an email from [Donald Trump, Jr.] saying ‘I’d love some dirt on Hillary from Russia.’ And could have threatened to reveal it at any time. Those around Trump clearly are naive about all of this.”

Schiff raises the possibility that this is only the tip of the iceberg when it comes to President Trump’s financial dealings with Russia. If true, and especially if Trump was engaged in money laundering that might violate U.S. laws (something yet to be proven), Schiff says “Russians would be well aware of it,” and could hold (or be holding) that over Trump’s head.

However, one does not need to prove Trump was engaged in any illegal business practices to conclude Trump was indebted to Russians. The Moscow Project explains the Trump relationship with Russia, thusly:

That Kremlin-linked entities invested significantly in Trump’s properties over the years is not inherently nefarious. Since the fall of the Soviet Union, wealthy Russians have invested heavily in real estate in the West, while Americans were in turn encouraged to invest in Russia. However, in the context of a president under several investigations for his connections to the Kremlin, Russia’s outsize role in Trump’s reemergence from financial tribulations that nearly destroyed his real estate empire merit additional attention. What emerges is the story of a man indebted to Russia through the oligarchs that President Vladimir Putin helped create and now controls.

Trump went from multiple bankruptcies at the end of the 1990s and early 2000s that made him an unacceptable credit risk to U.S. banks to breaking ground on more than a dozen projects up through 2012. “Given that Trump has defied decades of political tradition by assiduously refusing to release his tax returns, it’s difficult to truly get to the bottom of his finances. But the public record is more than enough to demonstrate that the answer, in part, lies with Russia.”

The more Trump denied any link or dependency on Russia during the campaign the more compromised he became, if he was in fact dependent on Russian money men. Once again, in this scenario, the Kremlin knew Trump’s “Nothing to see here!” was false, and Trump knew they knew.

Finally, one small nugget from the revelations this week highlight the extent of Trump’s problems. BuzzFeed News reports, “President Donald Trump’s company planned to give a $50 million penthouse at Trump Tower Moscow to Russian President Vladimir Putin as the company negotiated the luxury real estate development during the 2016 campaign, according to four people, one of them the originator of the plan. Two US law enforcement officials told BuzzFeed News that Michael Cohen, Trump’s personal lawyer at the time, discussed the idea with a representative of Dmitry Peskov, Putin’s press secretary.” It’s not known yet if Trump knew about this or how far the idea went, but offering and paying something of “value” to a foreign official to influence his actions (e.g., approve the deal) would be illegal under the Foreign Corrupt Practices Act. Who if anyone violated the FCPA cannot be determined by public facts, but if Sater and Cohen were throwing around “sweeteners” to get the deal done Russia would know  — and Trump would know the Kremlin knew.

The theories, and they remain theories at this point, suggest that there could be a treasure trove of information Russia holds over Trump’s head. If nothing Trump did was remotely illegal, he’d still be at the mercy of Putin because he has insisted so strenuously he has had no dealings with Russia. (Notice how Trump is now saying he “lightly looked” at the Trump Tower deal.) The notion of “collusion” — not a legal term — rests on the proposition that Trump’s interests were intertwined with a foreign power through a series of interactions and parallel moves dating to before the election, continuing through the Trump Tower meeting and through Trump’s public call in 2016 for Russia to release Hillary Clinton’s emails. That chain of events logically would be reason for so many people to tell so many untruths about Russia. Why else would they?

The frightful prospect of our commander in chief being indebted figuratively or literally to a hostile foreign power was the source of much concern to the Constitution’s framers, which resulted in the emoluments clause. If we cannot tell if Trump’s loyalties are solely to the United States (not a bit to Russia, a bit to Saudi Arabia, etc.), that is what Mueller, as part of his national security investigation, and Congress must find out. Without a clean bill of health — confirmation there was and is no “kompromat” — Trump has to go, one way or another.

Note: An earlier version of this story linked to an NPR report that stated Donald Trump, Jr. told Congress that Russia negotiations ended in 2014. That report has since been corrected and hence I’ve deleted reference to it.