WASHINGTON — A watchdog investigation into former special counsel Jack Smith over his prosecutions of President Trump is based on an “imaginary and unfounded” premise, Smith’s lawyers wrote in a letter obtained by the Associated Press on Tuesday. The letter marks the first response by Smith and his legal team to news that the Office of Special Counsel, an independent watchdog office, had launched an investigation into whether Smith engaged in improper political activity through his criminal inquiries into Trump. The attorneys told Jamieson Greer, the acting head of the office, that his investigation into Smith was “wholly without merit.”...