Would Donald Trump win an election today?

Would Donald Trump win a presidential election again today? Five experts - and a bookmaker - have their say.

There are many words to describe the 12 months since Mr Trump was elected.

Smooth is not one of them.

Mr Trump won despite getting almost three million fewer votes than Hillary Clinton.

Since then, there have been sackings, spats with NFL players, and sabre-rattling with North Korea.

His approval rating has fallen, and a special counsel is investigating the election itself.

But his supporters say a booming economy and improved border security prove they were right to take a gamble on an outsider.

So would the president win again now?

After shocking the world in November 2016, Mr Trump sent Allan Lichtman a handwritten note.

"Professor - congrats - good call," it said.

The note was written on a print-out of a Washington Post article from 23 September 2016.

In the article, Professor Lichtman said that - despite what most experts thought - Mr Trump was heading for the White House.

For the ninth presidential election in a row, he called it right. So how would Mr Trump do in a hypothetical election today?

"There are probably enough negative keys to predict his defeat," says Professor Lichtman, who teaches at American University.

The professor uses 13 "keys" to predict elections. They focus on the incumbent party, and cover the economy, scandal, the candidates' charisma, and other areas.

It is "very difficult" to call an early, hypothetical election, Professor Lichtman says. For example: one of his "keys" is the mid-term elections, which haven't happened yet.

But he says things aren't looking good for the president, with a lack of significant achievements and "scandals piling up", although the economy is currently a positive.

Mr Trump himself is also a drag on his chances, he says. "The very, very negative personal ratings would count against him."

The professor also downplays the importance of his opponent. "Only one of my 13 keys has anything to do with the opposing candidate," he says.

He thinks the scandals are so great, he wrote a book predicting Mr Trump's impeachment. Does he stand by that?

"You bet I'm standing by it," he says.

The Trafalgar Group - a small polling firm from Atlanta, Georgia - didn't just forecast Trump's win. They forecast the margin.

So, one year on, how would a rematch go?

"If it's the same match-up, I don't think there's any question," says Robert Cahaly, the group's senior strategist.

"Trump would win again."

Trafalgar has been "in the field" in 12 states this year, and always measures Trump's approval.

"Trump is still doing things that energise the people who brought him to the White House," says Mr Cahaly. Such as?

"The NFL thing. Anyone who thinks the NFL thing has hurt Trump among the people who won the swing states is completely crazy."

But what about the Russian links? The special counsel indicting Mr Trump's former campaign chairman?

"There are strong Russian connections with Hillary now," he says.

"The idea there's something fishy going on with Hillary, if nothing else, has counter-balanced any accusation against Trump."

But there is a caveat.

"My personal opinion has always been the Republican Party was very lucky Joe Biden wasn't the nominee.

"He appeals to the same demographic as Trump. It would have been a battle royal in Pennsylvania, Wisconsin, and Michigan."

Since 20 January, Gallup has carried out a daily poll, asking Americans whether they approve of the job the president is doing.

The numbers aren't great.

From June, Mr Trump's approval rating has usually been below 40%. On 29 October, it was just 33%.

But, says Frank Newport, Gallup's editor-in-chief, that doesn't mean he would lose a hypothetical election.

"He may be trending down a little, but if you look at the big picture from March or so, there's not a dramatic change," he says.

Gallup also tracked Mr Trump's popularity before the election. "He's unpopular now and he was unpopular then," says Mr Newport.

"He lost the popular vote (in 2016) and he managed to squeak in the electoral college.

"I wouldn't rule out the possibility, with the same opponent, he could pull that off again."

Mr Newport, however, will not put his neck on the line.

"I absolutely would not say he would win," says Mr Newport. "I neither confirm nor deny."

Helmut Norpoth - a political science professor at Stony Brook University in New York - also forecast Mr Trump's win in 2016.

"If you look at his approval rating, it's abysmal," he says.

"It's the worst any president has had [at this stage in his presidency]. It looks like a long shot - but it was a long shot for him to win in the first place."

So - in a hypothetical election against Hillary - who would he put his money on?

"I would bet that he would win again," he says. "He would beat her again."

Like Robert Cahaly from the Trafalgar Group, he thinks a different Democrat could have a better chance. But he doesn't know who that might be.

"I think Democrats don't realise what kind of a special candidate they had in Barack Obama," he says.

"They had Bill Clinton, they had Obama, but these guys don't come around every year. I don't know who, at this point, would have that kind of appeal."

The answer to Professor Norpoth's question, says Professor Barbara Perry, might be the previous vice-president.

"If tomorrow we put Donald Trump up against Joe Biden, I think Joe Biden would win," says Professor Perry, the director of presidential studies at the University of Virginia's Miller Center.

The problem with that plan, she says, is that Mr Biden will be 77 when the 2020 election is due. So if Mr Trump faced Mrs Clinton tomorrow?

"I would say, against Hillary, he would win," she says.

"His win (in 2016) was multi-causal of course. But what ultimately put him over the top was the Hillary factor in those three states - Pennsylvania, Michigan, Wisconsin."

On 18 October last year - almost three weeks before the election - Irish bookmaker Paddy Power was sure of the result. So sure, in fact, they paid out early.

Sadly for them, they called it wrong: they paid out on Hillary.

Their mistake cost them $4.5m. Since then, they've appointed a Head of Trump Betting, Joe Lee.

"On election day last year, Trump went in as a 4/1 underdog," he says.

"That more or less gave him a 20% chance. If we were going to market again, tomorrow or next week, we'd probably be closer to 50-50."

Trump has been strong on terrorism in the last few days, and on other topics that resonate with his core supporters, he says.

So, in the hypothetical election - Trump v Hillary part two - where would this bookmaker place his money?

"Oh, I'd absolutely go with Trump," he says. "No question or doubt about it."

Like the professors and pollsters, Paddy Power thinks Mr Trump's chances are "all down to the calibre of candidate the Democrats roll out".

The bookmaker has taken money on - among others - Mark Zuckerberg and Oprah Winfrey, while the Hawaiian congresswoman Tulsi Gabbard has been backed into 20/1.

For now, though, Mr Trump is calling the shots.

The bad news for the president?

Paddy Power has him 5/4 to be impeached - down from 9/4 before the special counsel's indictments.