(FILES) In this file combination of pictures created on September 10, 2020 shows US President Donald Trump (L) speaking as he makes his way to board Air Force One before departing from Andrews Air Force Base in Maryland on September 10, 2020, and Democratic presidential candidate Joe Biden speaking after a virtual meeting on safe school reopening, in Wilmington, Delaware, on September 2, 2020. - The volatile US presidential election enters a fierce new stage this week when Donald Trump and Joe Biden hold their first debate -- a television spectacle finally allowing Americans to witness the two antagonists head to head. Tuesday's clash, coming right after Trump defied Democrats and nominated a conservative to replace the late Supreme Court liberal icon Ruth Bader Ginsburg, could again upend an already nail-biting contest. Biden, 77, leads in polls against the Republican incumbent, both nationwide and in most of the crucial swing states set to provide the decisive electoral college count on November 3. (Photos by MANDEL NGAN and JIM WATSON / AFP)