John Dowd, a personal attorney to President Trump, resigned his post Thursday amid a shake-up in the president’s legal team as Trump has sought more firepower to deal with the special counsel’s Russia investigation. The resignation came Thursday, according to three people familiar with the decision. Dowd declined to comment. Dowd’s departure was a largely mutual decision made after the president lost confidence in his ability to handle special counsel Robert S. Mueller III’s investigation and Dowd became frustrated with Trump’s recent efforts to bring on new attorneys, they said. In recent weeks, Dowd clashed with the president, including an...