The trial of Paul Manafort, President Trump's former campaign chair, is officially underway. The many charges against him include tax and bank fraud. Special Counsel Robert Mueller likely has a strong case against Manafort, since the federal government rarely takes charges to court otherwise. But another way of knowing that the trial is unlikely to end well for Manafort is the tweetstorm by his former boss, in which Trump cursed Mueller and distanced himself from Manafort. Aside from demonstrating general contempt for legal restraint, Trump's threats portray a president who knows his former campaign chair is guilty, and is worried about what that means for him.

The most notable revelations from the first few days of Manafort's trial were about his lavish lifestyle. Witnesses described millions of dollars worth of home renovations, a multi-million-dollar residence purchased for his daughter, and more than a million dollars spent on suits in a five-year period. "By the time he bought that $15,000 ostrich jacket," observes Andrew Prokop of The Washington Post, "Manafort already owned a $9,500 ostrich vest."

Of course, this kind of extravagant spending might be gross, but it's not criminal. But what's important is not what Manafort bought, it's how he paid for it all. He spent nearly $1 million at the exclusive Manhattan boutique Alan Couture, and nearly all of those purchases were made by wire transfers from foreign accounts. According to a salesperson, Manafort was the only customer to pay this way. His spending on homes was also generally done through secret accounts.

The prosecution's theory is that Manafort used secret offshore accounts to fund his lavish lifestyle because he was hiding money for tax purposes and submitting fraudulent loan applications. Whether further evidence will persuade the jury remains to be seen, but it is enormously unlikely that all of this was on the level.

The president knows this, and it has him worried.

As Manafort was in federal court, Trump engaged in one of his patented Twitter tantrums, railing against the prosecution. He did not claim that Manafort would be vindicated and found innocent. Rather, he tweeted that "this is a terrible situation and Attorney General Jeff Sessions should stop this Rigged Witch Hunt right now, before it continues to stain our country any further."

Trump's surrogates, Jay Sekulow and Rudy Giuliani, were quick to clarify that the tweets did not represent a formal order for Sessions to fire Mueller. But that Trump would encourage his attorney general to stop an investigation that potentially implicates his own campaign is disturbing nonetheless.

Trump also played the victim with respect to Manafort. "Paul Manafort worked for Ronald Reagan, Bob Dole, and many other highly prominent and respected political leaders. He worked for me for a very short time," he complained. "Why didn't government tell me that he was under investigation." These excuses are absurd, to put it mildly. It's not exactly shocking that someone who had extensive ties to Eastern European oligarchs and plutocrats and agreed to nominally serve as Trump's campaign manager for free would be up to his neck in shady behavior.

Trump is narrowly correct, however, when he says "these old charges have nothing to do with Collusion." This trial is solely about accusations that Manafort defrauded the government and various financial institutions; in itself, the trial will not prove or disprove claims that Manafort or any other member of the Trump campaign colluded with Russian state actors interfering with the 2016 elections.

But Trump is nonetheless worried, as he should be. As David Eckles-Wade argues at Reuters, the Manafort trial is ultimately — if indirectly — "about how Russia moves money and buys influence." It seems that, owing to his lavish lifestyle, Manafort was in serious debt when he agreed to run Trump's campaign "for free." Considering his extensive ties to the Kremlin and his surreptitious meetings with Russians during the 2016 campaign, the implications of Manafort being found guilty are obvious.

Manafort's trial will not in itself prove collaboration between the Trump campaign and Russian electoral meddling. But it would be a major step in that direction, which is precisely why Trump wants Mueller's investigation shut down.