A close aide to Donald Trump is at the centre of an ugly clash between the White House and Senator Jon Ossoff, after the Democratic lawmaker drew the administration’s ire for highlighting the close nature of her relationship with the president. Natalie Harp, a 35-year-old executive assistant to the president, is little known to the public but a constant presence at Trump’s side, both in the White House and during weekend trips to his golf properties. In her role, she is seen as a gatekeeper,...