Donald Trump claims Hillary Clinton is 'protected by a rigged system' as US election comes down to the wire

His comments came after the FBI Director said it had not changed its views on Ms Clinton - lifting a cloud that has hung over campaign

Hillary Clinton and Donald Trump have made frantic appeals to voters as the 2016 presidential election campaign comes down to the wire.

On a day that was injected with fresh drama with comments from the FBI Director that it had not changed its conclusion that Ms Clinton should not be charged over the email controversy, the candidates hit the US heartland and seized some of their final opportunities to make their case to the nation.

Ms Clinton campaigned in Ohio with NBA star LeBron Jones, before moving on to New Hampshire where she was to appear with the father of slain US soldier Capt Humayun Khan.

Ms Clinton appeared with the sports star in Ohio (AP)

Speaking in Ohio, where polls show her in a dead heat with Mr Trump and where she campaigned last week with Jay Z and Beyonce, Ms Clinton said she had seen frustration and anger during the campaign but said “anger is not a plan. Anger is not going to get us jobs”.

Meanwhile, Mr Trump, who polls suggested was trailing his Democratic rival by up to five points, held rallies in five states, including Minnesota, which observers believe he has little chance of winning and said may reveal a sign of creeping desperation.

Speaking in Minneapolis, he said Ms Clinton was being “protected by a rigged system….she will be under investigation for a long, long time, likely concluding in a criminal trial”.

He later campaigned in Sterling Heights, Michigan, where polls suggest Ms Clinton has a five point lead.

In Iowa, Mr Trump said he was the “last chance” to fix immigration and trade.

Just 24 hours before election day, and with anywhere up to 30m Americans having already cast their vote, a flurry of recent polls give a small but solid lead to Ms Clinton. The final NBC-Wall Street Journal poll released on Sunday, put Ms Clinton on 44 points, with Mr Trump on 40. It placed Libertarian party candidate Gary Johnson at six per cent and Green Party Candidate Jill Stein had 2 per cent of support.

Those who carried out the poll, said Ms Clinton’s lead had fallen from the 11 point advantage she held over Mr Trump the last time the poll was conducted in the middle of October, before the FBI said it was reviewing new emails in its investigation of the former secretary of state.

Meanwhile, after running even with Mr Trump early last week, Ms Clinton was given a five-point lead in the latest Washington Post-ABC Tracking Poll. A final nationwide poll published by Politico placed Mr Trump three points behind his rival - scoring it 45-42. An average of all polls collated by Real Clear Politics gave Ms Clinton a narrower lead, just 1.8 per cent.

The nationwide polls do not tell the entire story of what is happening on the ground in battleground states. A calculation that takes into account such trends and battles by the FiveThirtyEight website, headed by pollster Nate Silver, gave Ms Clinton a 64.2 per cent chance of securing the White House.

Ms Clinton’s campaign manager, John Podesta, said her base of support among minority voters and the large number of early votes cast would lead to a win for her.

“We’ve had college-educated women voting in higher numbers, voting for her in higher numbers. Asian-Americans voting disproportionately,” he said on NBC’s Meet the Press.

Mr Trump's running mate, Indiana Governor Mike Pence, said that the campaign would accept a “clear outcome” to the election but said both campaigns reserved legal options if there was a disputed result.

“The campaign has made it very clear that a clear outcome, obviously, both sides will accept,” Mr Pence told Fox News. “But I think both campaigns have also been very clear that in the event of disputed results, they reserve all rights and remedies.”

Ten days ago, James Comey delivered a jolt to the electoral campaign by announcing that it was reopening its probe of Ms Clinton’s use of a private email server. It emerged agents were examining emails discovered on the laptop of Anthony Weiner, a disgraced former congressman who is the estranged husband of a top aide to Ms Clinton.

The revelation was leapt on by opponents of Ms Clinton, and subsequent polls showed her lead over Donald Trump begin to close. Yet on Sunday afternoon, Mr Comey published another letter to the Congressional Committee of Intelligence saying “we have not changed our conclusions that we expressed in July in regard to Secretary Clinton”.

Under intense pressure from all sides, Mr Comey said in his letter published on Sunday that his team had been working flat out to try and resolve the issue.

“The FBI investigative team has been working around the clock to process and review a large volume of emails from a device obtained in connection with an unrelated criminal investigation,” he said.

“During that process, we reviewed all of the communications that were to or from Hillary Clinton while she was secretary of state.”

He added: “Based on our review, we have not changed our conclusions that we express in July.”

Brian Fallon, a spokesperson for Ms Clinton, said on Twitter that the campaign was always confident that she would be cleared of any wrongdoing. “We were always confident nothing would cause the July decision to be revisited. Now Director Comey has confirmed it,” he said.

But Kellyanne Conway, Mr Trump’s campaign manager, asked why, if the Clinton campaign was so confident in the director, it had attacked Mr Comey “and his credibility”.