President Trump on Monday questioned whether the chairman of the House Intelligence Committee, Representative Adam B. Schiff, should be arrested for treason for his description of a phone call Mr. Trump had with the president of Ukraine during a recent congressional hearing.

A day earlier, Mr. Trump called for Mr. Schiff — the California Democrat who is the de facto head of an impeachment inquiry into the call — to be “questioned at the highest level for Fraud & Treason.”