WINSTON SALEM: Republican nominee Donald Trump said on Monday that if elected US president he would weigh an alliance with Russia against the militant Islamic State (IS) group but rejected any suggestion Russian President Vladimir Putin might be trying to help him win.

Speaking at a rally in Winston-Salem, North Carolina, Trump dismissed any suggestion that Putin's intelligence services might have had a hand in hacking the Democratic National Committee's (DNC) email system.

Emails leaked last week disclosed that some party officials had been in favor of former Secretary of State Hillary Clinton winning the Democratic presidential nomination over US Senator Bernie Sanders and sought ways to thwart Sanders.

The uproar over the WikiLeaks revelations prompted Debbie Wasserman Schultz to resign as DNC chairwoman, and Trump eagerly injected himself into the controversy.

Trump dismissed a charge from Clinton campaign manager Robby Mook that Russian hackers might have stolen the emails and leaked them to embarrass Democrats and help Trump defeat Clinton in the Nov. 8 election.

“I don't think it's coincidental that these emails were released on the eve of our convention here, and I think that's disturbing,” Mook told CNN's “State of the Union.” Trump dismissed what he called “one of the weirdest conspiracy theories” he said he had heard.

He said he had never met Putin. But over the course of his year-long campaign, Trump has praised the Russian leader and one of his top foreign policy advisers, retired Lieutenant General Michael Flynn, had dinner with Putin last December.

“When you think about it, wouldn't it be nice if we got along with Russia?” Trump said. “Wouldn't it be nice if we got together with Russia and knocked the hell out of ISIS?” he added, using another name for IS.

As it happens, skeptics in the U.S. government, European allies in the anti-IS coalition and the main Syrian opposition, distrustful of Russia's intentions, are questioning Secretary of State John Kerry's own latest proposal for closer U.S.-Russian cooperation against militant groups in Syria.

Trump assails air conditioning

Trump, kicking off a three-day campaign swing with his vice presidential running mate, Indiana Governor Mike Pence, returned to his freewheeling style after giving a scripted speech on Thursday accepting the Republican presidential nomination.

During an earlier event in Roanoke, Virginia, Trump labeled Clinton “low-energy”, the same characterisation he lobbed at Republican rival Jeb Bush; attacked her running mate, US Senator Tim Kaine of Virginia; and complained about the air conditioning in the hotel ballroom where he spoke.

“I think the ballroom and the people who own this hotel ought to be ashamed of themselves,” Trump said.

Trump made light of Democratic disunity as party loyalists gathered in Philadelphia on Monday to anoint Clinton as their nominee this week, after a week in which Republicans struggled to unite behind Trump at their convention in Cleveland.

Trump waved away Republican disunity as essentially isolated pockets of resistance and made an apparent reference to US Senator Ted Cruz, who was booed in Cleveland when he would not endorse Trump after losing to him in a bitter primary race.

“We had a couple people who probably destroyed their career, but who knows,” Trump said. “Look what's going on in Philadelphia. ... We had no riots, no nothing. It was unbelievable. I'll never forget it as long as I live.”

On Twitter, Trump added, “Wow, the Republican Convention went so smoothly compared to the Dems total mess.”