Even Trump's fans know he is in deep trouble.

As special counsel Robert Mueller closes in on Trump, Fox News’ in-house legal analyst is facing the reality that Trump is in deep trouble.

On Thursday morning, Judge Napolitano warned Trump “not to relax and not to rejoice” over the news that he was not a “target” of the Mueller investigation as of a month ago, sounded the alarm over Mueller’s questioning of Russian oligarchs, and delivered a crushing summation of where this is all going.

“They are on to something with respect to Russia,” Napolitano said. “In my column this morning, I talk about the three things they’re looking at.”

“So-called collusion, which is really a conspiracy,” Napolitano continued. “An agreement to accept something from the Russians, even if never delivered, the agreement is the crime.”

“They are also looking at obstruction of justice, was James Comey fired for a law enforcement purpose, or a corrupt purpose?” Napolitano said.

“Then they are looking at financial misdeeds, alleged financial misdeeds, committed by Mr. Donald Trump in the years before he was president,” he said. “But this conspiracy thing with the Russians has been fueled up since Rick Gates pleaded guilty, and has become their source for who in Russian intelligence was communicating with the campaign.”

Napolitano isn’t the only Republican to warn Trump not to relax, but what’s remarkable is that even though Napolitano clearly believes Mueller is “on to something,” he still wants Trump “to be able to be president, and not have this on his back.”

Napolitano has previously warned Trump not to speak with Mueller because he would perjure himself, and did so again Thursday morning when he warned that answering questions for Mueller would incriminate Trump.

This is a disturbing test case for Trump-era Republicans because Napolitano isn’t bothering to pretend Trump is innocent; he even seems convinced of his guilt. Every Republican can see what Napolitano sees, the evidence of collusion with the Trump campaign, the possible financial ties, and the blatant and repeated obstruction of justice by Trump.

But it is an open legal question whether a sitting president can be criminally indicted, which means the remedy for Trump’s misconduct would need to come from Congress.

If Mueller returns anything short of a criminal indictment, will a Republican-controlled Congress act to remove Trump from office? Or will they remain in his corner like his fans at Fox News?

So far, it doesn’t look good. It might look better in November.