US Republican presidential nominee Donald Trump said he was taking the gloves off in his battle against Democrat Hillary Clinton in the race for the White House after taking a scorching from speakers at this week’s Democratic National Convention.

Mr Trump wrapped up a five-day, seven-state campaign swing in Colorado yesterday, where for a fifth straight day his supporters chanted "lock her up" whenever he brought up Mrs Clinton's name.

Trump supporters say Mrs Clinton deserves to be prosecuted for her handling of US foreign policy as President Barack Obama's first-term secretary of state and for her use of a private email server while in that office.

All week Mr Trump has sought to tamp down the chants by stressing that his main goal is to simply beat Mrs Clinton in the 8 November presidential election.

But as the crowd chanted the slogan in Colorado Springs, Mr Trump finally relented.

"I'm starting to agree with you, frankly," he said. "No more Mr Nice Guy."

In Denver later, he changed his tune when he heard the chant.

"I'll tell you what I'd rather do, honestly, is just beat her on 8 November at the polls. She would be a disaster," he said.

Mr Trump was a punching bag at the Democratic convention in Philadelphia, which wrapped up Thursday night, as speaker after speaker - including some Republicans - said he lacked the temperament to be president.

Mrs Clinton herself said in her acceptance speech that the election represented a "moment of reckoning" for the country.

In Colorado Springs, Mr Trump got sidetracked by a couple of disputes from last year as he tried to rebut a Clinton campaign ad.

That ad uses video clip from Mr Trump's attack on Fox News anchor Megyn Kelly in protest of her questioning of him at a debate of Republican presidential contenders last August when he said afterwards that blood was "coming out of her eyes, coming out of her wherever."

"I was talking about her nose," Mr Trump said in Colorado Springs. "I wanted to get back on the issue of taxes" at the debate.

Mr Trump also brought up the case of disabled New York Times reporter Serge Kovaleski, whom he seemed to mock publicly in video used by the Clinton ad.

Mr Trump said he was depicting the reporter groveling to him.

"I didn't know he was disabled. I didn't know it at all. I had no idea," he said.

Campaign computers 'hacked'

Meanwhile, a computer network used by Mrs Clinton’s campaign was hacked as part of a broad cyber attack on Democratic political organisations, people familiar with the matter said.

The latest attack, which was disclosed yesterday, follows two other hacks on the DNC and the party's fundraising committee for candidates for the US House of Representatives.

A Clinton campaign spokesman said in a statement late that an analytics data programme maintained by the DNC and used by the campaign and a number of other entities "was accessed as part of the DNC hack".

"Our campaign computer system has been under review by outside cyber security experts. To date, they have found no evidence that our internal systems have been compromised," Clinton campaign spokesman Nick Merrill said.

Later, a campaign official said hackers had access to the analytics programme's server for approximately five days.

The analytics data programme is one of many systems the campaign accesses to conduct voter analysis, and does not include social security numbers or credit card numbers, the official said.

The US Department of Justice national security division is investigating whether cyber attacks on Democratic political organisations threatened US security, sources familiar with the matter said yesterday.

The involvement of the Justice Department's national security division is a sign that the Obama administration has concluded that the hacking was sponsored by a state, people with knowledge of the investigation said.