Donald Trump said on Monday morning that he would rule out running for the vice-presidency in the 2028 US election, an unorthodox approach that some of his supporters have floated to allow the Republican US president to serve a third term in the White House. “I’d be allowed to do that,” Trump said, in an exchange with reporters aboard Air Force One while traveling from Kuala Lumpur, Malaysia, to Tokyo, Japan, on Monday, the latest leg of a five-day trip to Asia which he hopes to cap with an agreement on a trade war truce with the Chinese president, Xi Jinping.