Clinton, Trump take gloves off in White House slog

Hillary Clinton and Donald Trump traded insults at opposite ends of the country Friday, taking their fight for the White House to rival battleground states and portraying starkly different visions of America.

One of the most divisive US campaigns in modern history is entering a new chapter with Republicans and Democrats having selected their nominees, leaving the candidates slogging it out before Election Day on November 8.

Clinton followed her historic acceptance speech on Thursday as the first woman presidential nominee for a major party with a rally in Philadelphia before embarking on a bus tour of Rust Belt states Pennsylvania and Ohio.

In Colorado, a key state out west, her Republican opponent promised "no more Mr Nice Guy," trashing Clinton's speech as "average," calling her a liar and promising to end the migration of Syrian refugees.

"I'm starting to agree with you," the 70-year-old told supporters chanting "lock her up, lock her up" in Colorado Springs. "I'm taking the gloves off," he said. "Just remember this Trump is going to be no more Mr Nice Guy."

Just over 100 days before the election, Americans are being asked to choose between two sharply polarized visions -- and between two monumentally unpopular candidates.

"I can't think of an election that is more important, certainly in my lifetime," Clinton told supporters at the rally in Philadelphia.

The 68-year-old Democrat portrays Trump as a threat to democracy, seeking to woo moderate Republicans repelled by the former reality TV star and shore up a coalition with progressives on the left of her party.

"Donald Trump painted a picture, a negative, dark, divisive picture of a country in decline," she said.

"I'm not telling you that everything is peachy keen -- I'm telling you we've made progress, but we have work to do."

She promises to focus on parts of the country that have been "left out and left behind" -- constituencies where declining living standards, fears about safety and lost jobs have fueled support for Trump.

Trump, who has never previously held office, portrays himself as the law and order candidate -- the outsider who will shake up an out-of-touch Washington, restore jobs, cut the deficit and end illegal immigration.

In Colorado, he goaded Clinton on her failure to hold a news conference since December and accused her of lying to the FBI over its investigation of her email scandal as secretary of state. (AFP)