President Trump unloaded on House Speaker Nancy Pelosi on Thursday, calling her "a mess" as the White House escalates political attacks over Democratic investigations of Trump.

"She's a mess, look, lets face it," Trump said, accusing Pelosi of not understanding the pending United States-Mexico-Canada Agreement on trade, which must pass the House.

"She does not understand it. And [administration trade officials] sort of feel she is disintegrating before their eyes," Trump said.

Trump called the California Democrat "crazy Nancy," and questioned her mental state, saying, "She's not the same person; she's lost it."

Trump defended his conduct during a Wednesday encounter with Pelosi and Senate Minority Leader Chuck Schumer, D-N.Y., which Pelosi described as a "temper tantrum."

He rebutted Pelosi's call for a Trump family intervention for the president, calling it a "very sort of nasty type statement."

"It's a do nothing Congress. The Democrats have done nothing in the House. They have done absolutely nothing other than investigate," he said.

[Also read: Pelosi: 'I pray for the president of the United States,' Trump responds]