TOPSHOT - US President-elect Joe Biden waves while leaving the St. Joseph on the Brandywine Catholic Church after attending Mass in Wilmington, Delaware on November 15, 2020. - President Donald Trump appeared accidentally to admit his election defeat in a tweet on Sunday morning -- before reversing course to claim he won, and once again push unsubstantiated claims of mass fraud in the vote.Trump has refused to concede the November 3 US election to challenger Joe Biden, and repeatedly said he intends to overturn the result through legal cases.His aides say he is preparing for a second term in office despite the vote count confirming Biden's clear victory. (Photo by ROBERTO SCHMIDT / AFP)