Donald Trump's former personal valet Walt Nauta could "flip" on Trump, which would result in "lights out" for the former president's legal case, a constitutional attorney said on Fox News on Friday.

George Washington University Law professor Jonathan Turley, who has been a frequent defender of Trump but has recently acknowledged the severity of the legal threat posed by Jack Smith's charges, appeared on Fox to address the question of how things could get worse for the former president, who was hit with 37 counts in the case over classified document handling.

Nauta was also indicted.

The question, according to Turley, is, "Can this get worse? Because it's pretty darned bad," he told the Fox host.

"And the answer is: 'Yeah.' This co-defendant, Nauta, if he were to flip, could really put the lights out on the defense," he said. "This indictment is clearly designed to concentrate his mind again on whether he will cooperate."

Turley added that the "key" for the defense team is that "they've got 37 counts in a 76-year-old client."

"In this deluge, they've got to walk through those counts and not get wet," he added. "They can't have a single count that actually lands with a guilty verdict because these are coming with ten to 20 year maximum sentences."

Watch below or click here.