<sod >US Secretary of State Rex TillersonÃÂÃÂ has said he will stay in the Trump administration as 'long as he is useful' as he denied reports that he had called the president a "moron".< eod>< sod > US Secretary of State Rex Tillerson has said he will stay in the Trump administration as "long as he is useful," but he did not deny reports that he had called the president a "moron".< eod>