Donald Trump called Hillary Clinton "very unstable" at a rally in Miami today, a campaign event in which he went hard on the attack against the Democratic presidential nominee.

"She's got bad judgment," Trump said. "Personally, I think she's a very unstable person." He did not substantiate his claim.

The Republican nominee, without presenting specific evidence, also said Clinton "probably" received a heads-up about questions in her debates against him. He pointed to the revelation by the anti-secrecy website WikiLeaks that Donna Brazile, the interim Democratic National Committee chair, provided Democratic primary debate questions to Clinton's campaign.

Trump also noted other unflattering releases by WikiLeaks and predicted that more damaging ones might be on the way. He also mentioned the FBI's revived investigation into Clinton's email practices at the State Department.


"Did you hear about this little event?" Trump said.

Trump told the crowd to vote with urgency and "pretend we're slightly behind," though some recent Florida polls do show him trailing Clinton. He added, "We don't want to blow this."

At one point, Trump appeared to single out NBC News reporter Katy Tur for criticism, as he has done before.

"We have massive crowds. There's something happening. They're not reporting it. Katy, you're not reporting it, Katy. There's something happening, Katy. There's something happening, Katy," Trump said.

As animosity against the media has grown at recent Trump rallies, his has added a larger buffer zone and more security between reporters and the crowds. But at the Miami rally, there was no buffer, and screaming supporters were just inches away from reporters. One man near the press pen continued screaming menacing things at "Katy" as the rally continued.

Meanwhile, President Barack Obama expressed concern in a radio interview broadcast that too few African-Americans are voting this time around, and he pressed black voters to turn out for Clinton to protect the policies he has implemented.

"I'm going to be honest with you right now, because we track - we've got early voting, we've got all kinds of metrics to see what's going on. And right now the Latino vote is up, overall vote is up, but the African-American vote right now is not as solid as it needs to be," Obama said on "The Tom Joyner Morning Show," a syndicated programme with many African American listeners.

Obama framed the election as not only a race between Clinton and Trump but one in which his record is on the line.

"I need everybody to understand that everything we've done is dependent on being able to pass the baton to somebody who believes in the same things I believe in," the president said.

Obama also briefly addressed for the first time the FBI's reopened investigation into Clinton's emails, saying in an interview with NowThis News that the agency does not "operate on innuendo" and emphasising that there is no evidence that the Democratic presidential nominee had violated the law.

The Clinton campaign announced that it is doubling its Arizona advertising investment to US$1 million for the final week of the campaign. A Democratic nominee for president has not won Arizona since Bill Clinton in 1996, but polls show a competitive contest there.

Trump's children were fanning out across key battlegrounds to campaign on his behalf. Donald Trump jnr, Ivanka Trump, Tiffany Trump and Eric Trump were covering Colorado, North Carolina, Michigan, Ohio and Pennsylvania.

At his rally, Trump criticised both Bill and Hillary Clinton, saying, "If Hillary Clinton were to be elected, it would create an unprecedented and protracted constitutional crisis. Haven't we just been through a lot with the Clintons? Right? Remember when he was impeached for lying? He can't practice law, he doesn't have the right to practice law. Didn't we just go through this?"

As Trump spoke, a man in the crowd kept screaming, "He's a rapist!"

CNN - Clinton 49, Trump 47
Quinnipiac - Clinton 46, Trump 45
TargetSmart - Clinton 48, Trump 40

North Carolina
Quinnipiac - Clinton 47, Trump 44

Quinnipiac - Trump 46, Clinton 41

Quinnipiac - Clinton 48, Trump 43
Monmouth - Clinton 48, Trump 44
CNN - Clinton 48, Trump 44
Susquehanna - Clinton 45, Trump 43

CNN - Trump 49, Clinton 43
Political Polls - Clinton 45, Trump 38

CNN - Trump 49, Clinton 44

Mitchell - Clinton 50, Trump 43

Winthrop - Clinton 44, Trump 39

Marquette Law School - Clinton 46, Trump 40

Emerson - Clinton 44, Trump 41
Political Polls - Clinton 44, Trump 37