Blow-by-blow: Trump scrambles to regain momentum in second presidential debate

Scroll down for a video replay of the second presidential debate.

UPDATE: A CNN/ORC snap poll had Hillary Clinton winning 57-34%. But 63% said Donald Trump did better than they expected.

The second debate ends with both candidates shaking hands, a gesture missing at the beginning.

The most venomous of the debates came to an enforced state of cordiality because each was asked what they most admired in in each other.

Mrs Clinton praised Mr Trump for the respect he shows his family and, after thanking her for that compliment, said, in turn, he admired that she doesn't give up.

"She doesn't quit, she doesn't give up. I respect that. I tell it like it is. She is a fighter."

Energy companies and the loss of jobs proves to be the second to last question, one which gives Mr Trump to promote his pro-business credentials.

"The EPA [Environmental Protection Agency] is so restrictive it's putting our energy companies out of business," he says.

A persistent intervention by moderator Martha Raddatz finally separates the candidates from talking over each other for a question on selection of Supreme Court justices to replace the late Antonin Scalia.

Mr Trump backs a similar candidate from the right while Mrs Clinton speaks at length on the need for someone prepared to stand up to big business and restore campaign finance restrictions.

The debate is ending on the same note as the first – who is most fit to be president?

Asked whether he can be a "devoted president" to everyone in the country, he replies: "Absolutely," he says. "She calls our people deplorable."

He then cites trade, noting that the NAFTA free trade agreement was signed by Mrs Clinton's husband.

"I would be a president for all of the people. African Americans, the inner cities. Devastating, what is happening to our inner cities," Mr. Trump says, citing high unemployment, bad schools and a bad urban job market.

"She has tremendous hate in her heart."

Mrs Clinton says she regrets the word "deplorables" but says her quarrel was not with Mr Trump's supporters but with him.

Russia returns
"I've stood up to Russia," Mrs Clinton says as the subject returns in the context of what the candidates would do about Syria.

She also says she would push for Russia to be investigated for war crimes in the bombing of Aleppo.

This winds up Mr Trump, who turns to tactics in the wider war, including the retaking of Mosul in Iraq from Isis.

Taxation is back
Taxation policies have returned to round off the first hour.

Mr Trump is asked specifically about how he would change the tax code. He cites the carried interest deduction and then says Mrs Clinton, as a US senator, should have changed the tax code during her time in government.

"Why didn't you change it when you were a senator? The reason you didn't, all your friends take the same advantage, as I do," he says.

He says he plans to cut taxes for the middle class while Mrs Clinton will be raising them for the middle class. 

Russia's been accused of working to elect Donald Trump, Hillary Clinton says in a trenchant attack on that country's role in hacking US websites and the Syrian civil war.

She also added Wikileaks for releasing her emails as secretary of state as part of an attempt to influence the presidential election – "they're not working to elect me."

'Radical Islam'
"We are not at war with Islam," Mrs Clinton avers in response to another key issue in the election campaign: how to protect America as terrorist acts committed by Muslims.

She says Mr Trump's plan to ban Muslim immigration is impractical. "We are a country founded on the ideal of religious freedom."

This question was relished by Mr Trump: "Muslims have to report the problems when they see them," citing terrorist attacks in Orlando, San Bernardino and the 9/11 attacks in New York.

He also accuses Mrs Clinton and Mr Obama of not saying the name of radical Islam.

"You have to be able to state what the problem is or at least say the same. She won't say the name and President Obama won't say the name. But the name is there. It's radical Islamic terror."

Equilibrium has returned with the candidates both agreeing the Affordable Care Act ("Obamacare") needs changing as both respond to a question.

While Mrs Clinton suggests a number of measures to improve its shortcomings, Mr Trump describes the whole scheme as a "fraud" and a "disaster" that needs repealing,

This is an issue where Democrats and Republicans are in two distinct camps.

Debate degenerates
After half an hour the debate has degenerated into a series of more personal, aggressive, vituperative remarks than seen previously.

"Because you'd be in jail," Mr Trump said at the end of one accusation as the subject moved on to the Clinton emails.

He made the surprise announcement he would appoint a special prosecutor to look into it and renewed accusations that she began the "birther" rumours about President Obama. 

Mr Trump is responding to Mrs Clinton's broadside on his recently exposed behaviour and turned his fire on former president Bill Clinton, who is in the audience.

"Mine are words, his was action. There has never been anybody in the history of politics in this nation that has been so abusive to women," Mr Trump says.

"It's just words. It's just words," he says of Mrs Clinton's remarks. "Those are words I've been hearing for many years." He says Mrs Clinton has failed to bring jobs back to upstate New York, failed to revitalise and secure urban America.

"I'm going to help the African Americans, I'm going to help the Latinos, Hispanics. I'm going to help the inner cities," he says.

Mrs Clinton has gone on the offensive against Mr Trump's fitness to be president, repeating a litany of allegations about his attitude, not just to women but also to Latinos, people with disabilities and others.

"We will respect one another ... and we will celebrate our diversity," she says. "This is the America I know and love."

Co-moderator Anderson Cooper introduced the first question about whether candidates saw themselves as role models for youth in their behaviour on the previous debate, with Hillary Clinton answering first.

She has has long been saying that Mr Trump's temperament and character render him unfit to be president. But he began his answer by agreeing with everything Mrs Clinton said.

Mr Cooper quickly raised the issue of Mr Trump's "locker room" talk but the candidate deflected this on to more current issues such as how he would handle Isis.

"I have tremendous respect for women, " he said, adding he would make America "safe again."

Earlier:

Today’s second presidential debate in the US will be held against a background of turmoil in the Republican Party.

A last-minute breaking development has seen Donald Trump hold a last-minute press conference with three of Bill Clinton's most prominent accusers.

This follows the release of historic videos and audio recordings of Donald Trump making lewd and degrading comments about women.

As a result, leading Republicans have made last-ditch efforts to sabotage Mr Trump’s candidacy or have withdrawn their personal support.

But there’s no concerted effort and, for his part, Mr Trump says he won’t be standing down and will ride out the controversy.

Meanwhile, two new polls in Pennsylvania and Florida show Democratic candidate Hillary Clinton pulling ahead.

In Pennsylvania she is 12 points ahead (49%-37%) among likely voters and in Florida three points ahead (45%-42%).

The debate will be held at Washington University in St Louis and runs for 90 minutes without commercial breaks from 2pm (NZ time).

Unlike the first studio-style debate, it will be held in the town-hall format, with half of the questions being posed by the audience.

Moderators Martha Raddatz of ABC News and Anderson Cooper of CNN will ask the other half.

Participants will be uncommitted voters selected by the Gallup Organisation.