Clinton vs Trump: 90-minute debate could change America

It is 90 box-office minutes that could change America.

With Hillary Clinton and Donald Trump virtually tied in recent national polls, they enter the debate as the two least popular presidential candidates in modern history.

Tonight's debate, which will be moderated by NBC's Lester Holt, will see the two candidates speak on America's direction, achieving prosperity and the country's security.

These will be covered across six 15-minute segments before an audience at New York's Hofstra University.

It has the potential to be a bloody battle, with a Superbowl audience of more than 100 million people forecast.

In the blue corner, a career politician, an experienced debater, trying to stem an apparent surge in popularity for her rival.

In the red corner, a reality TV star, who successfully disposed of his opponents by giving them nicknames on stage, now needs to prove he has the temperament to be commander-in-chief.

Mrs Clinton has been doing her homework - studying her rival and practising going into battle with him.

In the role of Mr Trump has been Phillip Reines, who served as deputy assistant secretary of state under Mrs Clinton and is known in Washington circles for his bullish, combative personality.

Jim Manley, a Democratic strategist and former Senate aide, told Sky News that Mrs Clinton "needs to be aggressive".

"She can’t just let Trump be Trump," he said.

"People want to see her looking strong and challenging him."

Fact-checking any false claims, he says, is essential, but she must also present a positive vision for America.

The stakes are high for both candidates, but Mrs Clinton arguably has more to lose.

After her recent diagnosis of pneumonia, her appearance will also be scrutinized and Richard Nixon’s sweaty, unshaven look in the first ever televised debate, is a potent reminder that how you look, matters.

Mr Trump, appears to be looking for a fight before he’s even stepped in the ring, taunting his opponent by threatening to bring Gennifer Flowers along, with whom Bill Clinton admitted to having a sexual relationship decades ago.

At a time when he needs to present a presidential image, it is a risky move - potentially alienating women voters.

The billionaire businessman, who has consistently railed against convention, has been taking a more relaxed, on the-fly approach to his first ever debate.

But the Republican nominee has, we’re told, been watching Mrs Clinton’s "best and worst" TV moments. His TV background and ability to deliver pithy one-liners with populist appeal, could serve him well.

Bret Baier, who was a moderator in the Republican primary debates, tells me Mr Trump is "better at the soundbites".

Political commentators have been filling the airwaves with talk of Mr Trump's bar being low and expectations few. His own surrogates are also playing down his chances.

His biggest challenge will be staying on message. If he can do that, it may well be viewed as a victory.

In a race dominate by personality, this is a chance to debate policies.

By the end, we will find out if details make a difference.

:: Watch a special programme on the first US presidential debate on Sky News from 11pm tonight. You can also see a replay of the entire debate on Tuesday at 8.30am-10am and 2.30pm-4pm. It will also be available on our On Demand service.