Democrat Hillary Clinton accused Republican Donald Trump of racism, sexism and tax avoidance during a heated presidential debate that could reshape the 2016 campaign for the White House.  Trump, a real estate tycoon making his first run for public office, said Clinton's long years of service represented "bad experience" with few results and suggested her disavowal of a trade deal with Asian countries was insincere.  For Trump, 70, the debate was a chance to appear disciplined. For Clinton, 68, it was an opportunity to reassure voters she could be trusted. It remained to be seen how voters would judge their performance.  In a sign investors saw Clinton as the winner, Asian shares recouped early losses on Tuesday and the US dollar edged away from a one-month trough against the yen. Markets have tended to see Clinton as the candidate of the status quo.  In one of the more heated exchanges, the two candidates attacked each other for the controversy Trump stoked for years over whether President Barack Obama was born in the US.  The president, who was born in Hawaii, released a long form birth certificate in 2011 to put the issue to rest. Only this month did Trump say publicly that he believed Obama was US-born.  "He (Trump) has really started his political activity based on this racist lie that our first black president was not an American citizen. There was absolutely no evidence for it. But he persisted. He persisted year after year," Clinton said.  Trump repeated his false accusation that Clinton's failed 2008 presidential campaign against Obama had initiated the so-called "birther" issue.  "Nobody was pressing it, nobody was caring much about it ... I was the one that got him to produce the birth certificate and I think I did a good job," Trump said.  African-American voters overwhelmingly support Clinton, but Trump in recent weeks has said he believes his policy agenda would benefit them and said the policies of Obama and Clinton had failed to help black Americans.  He said Clinton's arguments were disingenuous.  Clinton wore a red pantsuit, and Trump wore a dark suit and a blue tie to the encounter that could shift the course of the tight race for the November 8 election. She called him Donald. He called her Secretary Clinton for much of the debate before switching to her first name.  Toward the end of the debate, Trump said Clinton did not have the endurance to be president.  "She doesn't have the look, she doesn't have the stamina," he said.  Citing her own public record, Clinton retorted: "As soon as he travels to 112 countries and negotiates a peace deal, a ceasefire, a release of dissidents ... or even spends 11 hours testifying in front of a congressional committee, he can talk to me about stamina."  Each accused the other of distortions and falsehoods and urged viewers to check their campaign websites for the facts.  Clinton called the New York businessman's tax policies "Trumped-up trickle-down" economics and Trump accused the former secretary of state of being "all talk, no action".  Clinton knocked Trump for not releasing his income tax returns and said that decision raised questions about whether he was as rich and charitable as he has said.  Trump attacked Clinton for her trade policies and said she would approve a Trans-Pacific Partnership despite opposing it as a candidate.  "You were totally in favour of it, then you heard what I was saying, how bad it is, and you said, 'Well, I can't win that debate,' but you know that if you did win, you would approve that," the former reality TV star said.  "Well Donald, I know you live in your own reality, but that is not the facts," she said.  Moderator Lester Holt struggled to rein in the candidates, with discussions about trade policy suddenly shifting to the fight against Islamic State as Trump accused Clinton of giving away information to the enemy by revealing on her website how she planned to defeat the group. Clinton said that unlike Trump, she at least had a plan for fighting Islamist militants.  Opinion polls have shown the two candidates in a very tight race, with the latest Reuters/Ipsos polling showing Clinton ahead by 4 percentage points, with 41 percent of likely voters.
Monday night's debate (Tuesday 11am AEST) will be the first time Hillary Clinton and Donald Trump go toe-to-toe in front of a massive television audience.