CONROE, Texas (AP) — As he prepared to tee off at one of his Florida golf courses, a fellow player introduced Donald Trump as the "45th president of the United States."

"45th and 47th," Trump responded matter-of-factly, before hitting his drive.

The quip — a moment of levity on the links captured on shaky cellphone video — was a reminder that the former president often has another presidential run on his mind. But the declaration belied the growing challenges he's confronting as a series of complex legal investigations ensnare Trump, his family and many associates.

The probes, which are unfold...