Washington (CNN) What was meant to be a celebratory tour of the Midwest on Thursday turned sour for President Donald Trump when he learned federal prosecutors were looking to question his company's longtime financial boss.

Phoning his attorneys and other confidantes from behind his desk on Air Force One, Trump sought more details about what precisely the Southern District of New York wanted to know from Allen Weisselberg, the Trump Organization's chief financial officer who is so close to the President he once appeared on "The Apprentice."

For Trump, the news added another unfortunate layer to his growing frustration at the swirling legal questions now clouding both his administration and his business. Trump's mood, people inside the White House say, has grown dark as his longtime fixer Michael Cohen executes a very public breakup . Even as he worked to exude confidence about a roaring economy and handshake deal with Europe , the encroaching troubles made for another agony-and-ecstasy week.

"They're dying to see us make a little bit of a mistake," Trump lamented Thursday from inside a Granite City, Illinois, steel plant, where he was hoping to exult in positive economic news in front of a supportive crowd. Aides said they organized the tour hoping to spotlight policies that have helped boost American manufacturing. Privately, some also concede getting Trump on the road is a way to distract him from the persistent drip-drip of the Russia investigation.

But even in the heartland, his mind turned again to his troubles back home. Glaring at a row of television cameras, he mimicked his media critics and flashed irritation at the spotlight that comes with his office.

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