U.S. presidential candidate Hillary Clinton said on Thursday the challenges facing Americans demand steady leadership and a collective spirit, contrasting her character with what she described as a dangerous and volatile Donald Trump.

In the biggest speech of her more than 25-year-old career in the public eye, Clinton accepted the Democratic presidential nomination for the Nov. 8 election with a promise to make the United States a country that worked for everyone.

"We are clear-eyed about what our country is up against. But we are not afraid," she said.

Source: b'Hillary Clinton (right) with US President Barack Obama | Source: Reuters\xc2\xa0'

She presented a sharply more upbeat view of the country than her rival Trump did when he was formally nominated for president at last week's Republican convention, and even turned one of Republican hero Ronald Reagan's signature phrases against the real estate developer.

"He's taken the Republican Party a long way, from 'Morning in America' to 'Midnight in America,'" Clinton said. "He wants to divide us - from the rest of the world, and from each other."

While her speech lacked the electrifying qualities of President Barack Obama and a parade of other prominent Democratic speakers, Clinton spoke authoritatively and with self-assurance in her pitch to the American public.

She acknowledged some people still do not know her well.

"I get it that some people just don't know what to make of me. So let me tell you. The family I'm from, well no one had their name on big buildings," Clinton said in a reference to Trump. She said her family were builders of a better life and a better future for their children, using whatever tools they had and "whatever God gave them."

Source: b'A file photo of Hillary Clinton | Source: Reuters'

As she prepared to deliver her speech, people familiar with the matter said the FBI is investigating a cyber attack against another Democratic Party group, which may be related to an earlier hack against the Democratic National Committee.

The previously unreported incident at the Democratic Congressional Campaign Committee, or DCCC, and its potential ties to Russian hackers, are likely to heighten accusations, so far unproven, that Moscow is trying to meddle in the U.S. election to help Trump.

Clinton said it would be her "primary mission" to create more opportunities and more good jobs with rising wages, and to confront stark choices in battling determined enemies and "threats and turbulence" around the world and at home.

Source: b'A file photo of Democratic presidential nominee Hillary Clinton addresses the Democratic National Convention via a live video feed \xc2\xa0| Source: Reuters'

Clinton embraced her reputation as a policy wonk, offering a litany of proposals for tuition-free college, infrastructure investment, immigration reform, gun control, affordable child care, paid family leave and more.

Clinton also reached out to Republicans and to followers of primary rival Bernie Sanders, the democratic socialist U.S. senator from Vermont. His supporters chanted at times during her speech only to be drowned out by her supporters.

"Your cause is our cause," she said.

Source: b'A file photo of Donald Trump | Source: Reuters'

Meanwhile, Trump, a 70-year-old reality TV show host who has never held political office, is running just ahead of Clinton in a RealClearPolitics average of recent national opinion polls. They both garner high "unpopularity" ratings.

At a rally in Cedar Rapids, Iowa, Trump said he was being criticized at the Democratic convention by people who had been friendly to him before.

"I think we'll stay here all night because I don’t really want to go home and watch that crap," he said.

Trump has portrayed the country as being under siege from illegal immigrants, crime and terrorism and as losing influence in the world. He has proposed a temporary ban on Muslims entering the country and a wall along the border with Mexico to keep illegal immigrants out.