US President Donald Trump on Sunday threatened a prominent NBC broadcast journalist with possible punishment by US media regulators as the Republican expressed disappointment with coverage of his candidate endorsements ahead of November’s midterm elections.Trump took to his Truth Social platform to attack Kristen Welker as the “unpopular ‘hostess’ of the once great Meet the Press talk show.He objected to her having said the president had had “mixed results” on his endorsement of political...