* Trump bids to shift dynamics of race that has Biden leading * Pair have 90 minutes to make closing arguments to America * Final presidential debate – follow it liveDonald Trump and Joe Biden will face off for a final time during Thursday night’s presidential debate in Nashville – perhaps the last chance for the president to shift the dynamics of a race that increasingly favors his Democratic opponent with less than two weeks until election day.The candidates will have 90 minutes to make their closing arguments to the nation, amid a pandemic that has killed more than 220,000 Americans and infected millions more, including the president. In part due to the pandemic, more than 40 million Americans have already cast their ballot, shattering records and leaving Trump an increasingly narrow window to reset the debate.Despite the cascading public health and economic crises, Biden has maintained a steady lead over the incumbent, according to public opinion polls, while Trump has struggled to outline his vision for a second term and grapple with voters’ disapproval of his response to the pandemic.Trump’s challenge will be to demonstrate that he can keep his cool after a chaotic and widely criticized first presidential debate in Cleveland last month, during which he repeatedly interrupted Biden. Trump’s angry performance was poorly reviewed, and Biden only strengthened his polling lead following the clash.This time, each candidate will have his microphone muted while his rival delivers a two-minute response to each of the six predetermined debate topics, which include: fighting Covid-19, American families, race in America, climate change, national security and leadership.The button will not be used during the subsequent open debate segment of each discussion, even if a candidate interrupts or talks over his opponent.Trump’s campaign attacked the independent Commission on Presidential Debates over the change, calling it an “attempt to provide advantage to their favored candidate”. The campaign also contested the topics, and Trump has complained that the moderator, the NBC News correspondent Kristen Welker, was “extremely unfair”.Biden and Trump were tested for the coronavirus before the debate Thursday, and both results were negative.In the final weeks of the campaign, Trump has returned to his attacks on Biden as a corrupt Washington insider, and cast his Democratic rival as the patriarch of the “Biden crime family”. By contrast, Biden has hammered the case that Trump’s handling of the coronavirus is evidence that he is not fit to be president, a theme Barack Obama stressed during his first return to the campaign trail on Wednesday.Few of the president’s political enemies get under his skin like his predecessor, and Obama was unsparing in his ridicule of the president. “Eight months into this pandemic, cases are rising again across this country” Obama said at a drive-in rally in Philadelphia. “Donald Trump isn’t suddenly going to protect all of us. He can’t even take the basic steps to protect himself.”A second debate, scheduled to take place in Miami, was cancelled when Trump abruptly withdrew after the commission announced that it would be held virtually due to Trump’s Covid diagnosis. The candidates held dueling town halls instead.