With less than a month to go before the Nov 8 United States presidential election, two Singapore observers are increasingly confident that this election is Democratic candidate Hillary Clinton's to win.

This comes after Mrs Clinton and Republican candidate Donald Trump faced off in their second debate marked by hostility, aggression and personal attacks.

Political scientist Elvin Lim of the National University of Singapore cited three polls done over the weekend, two of which put Mrs Clinton well ahead of her opponent.

"Polls are very accurate," said Associate Professor Lim, adding that on average, the difference between the last poll and the result is between 3 per cent and 5 per cent.

"And voting has already started. The polls are not just polls now - they reflect actual voting on the ground," he added, noting that early voting has begun in the US.

Prof Lim, who has written two books on American politics, was speaking at a panel organised by the Singapore Press Club, and moderated by Singapore Press Holdings' deputy chief executive Patrick Daniel.

Also on the panel discussing the US presidential race were Mr Steven Okun, who sits on the board of the American Chamber of Commerce in Singapore, and Ms Tina Datta of Republicans Overseas Singapore.

Mr Okun said a factor making him confident of Mrs Clinton winning is that swing states which tend to decide an election have become more diverse, with more Hispanics and Asians. "When Donald Trump says he is going to build a wall or have extreme vetting for immigrants, he is not reaching out to the Hispanics," he said.

The trio also discussed the rise of Mr Trump, who has used his outsider status to appeal to crowds.

Mr Okun, who served in former president Bill Clinton's administration, said the Vietnam War and the Watergate scandal in the 1960s and 1970s marked the most divisive period in US history, and "caused a massive switch in the trust that Americans had in our system".

This has allowed candidates with no political experience to rise.

"We no longer trust government, the media, and any institution like we used to," he said. "We want change, we want outsiders, we don't trust Washington like we used to."

Mr Trump's rise reflects the anger and frustration Americans feel about issues such as job losses, said Ms Datta. She said she had a hard time accepting Mr Trump as the party's candidate, but "perhaps he may not have got the support if (the situation in America) wasn't as bad as people perceive it to be".

On what a Trump presidency means for Asia, Prof Lim said China may not view Mr Trump negatively.

"If you read their reports, the Chinese kind of like him," he said.

"They may well want someone who is an isolationist - who doesn't really care to go out there to defend America's allies as much, at least, as the 'hawkish' Hillary Clinton."