PHILADELPHIA, July 28, (Reuters): U.S. presidential candidate Hillary Clinton said on Thursday Americans faced challenges at home and abroad that demand steady leadership and a collective spirit, and attacked Republican Donald Trump for sowing fear and divisiveness.

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.

She presented a sharply more upbeat view of the country than the dark vision Trump offered 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. He's betting that the perils of today's world will blind us to its unlimited promise."

The speech was Clinton's turn in the spotlight after three days of electrifying appearances by President Barack Obama, Vice President Joe Biden and first lady Michelle Obama, and Clinton acknowledged that 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."

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.

"America is once again at a moment of reckoning. Powerful forces are threatening to pull us apart. Bonds of trust and respect are fraying," said Clinton, a former secretary of state. "No wonder people are anxious and looking for reassurance - looking for steady leadership."

Clinton, who is vying to be the first woman elected U.S. president, called her nomination "a milestone" and said she was happy for grandmothers and little girls and "everyone in between."

"When any barrier falls in America, it clears the way for everyone," the 68-year-old Clinton said in a speech that capped the four-day nominating convention.

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.

Inside the arena, it sounded at times more like a traditional Republican convention than a Democratic one. During retired General John Allen's remarks, chants of "USA!" filled the hall and large flags were brought in to be waved. Speakers, some of whom included military and police officers, made frequent mentions of religion and patriotism.

"I certainly know that with her as our commander-in-chief, our foreign relations will not be reduced to a business transaction, I also know that our armed forces will not become an instrument of torture," said Allen.

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.

Khizr Kahn, a Muslim whose son was one of 14 Muslims killed while serving in the military since the Sept. 11, 2001, attacks, drew cheers when he pulled out a pocket copy of the U.S. Constitution and said he wanted to show it to Trump.

"Hillary Clinton was right when she called my son the best of America. If it was up to Donald Trump he never would have been in America. Donald Trump consistently smears the character of Muslims," he said.

U.S. Senator Sherrod Brown of Ohio called Trump a hypocrite who talked about opposing free trade deals to protect American workers but had the products sold by his companies made overseas.

"Now I've been fighting for a trade agenda for more than 20 years that puts American workers first and I can tell you that in all those years I've never ever seen Donald Trump," said Brown, one of the most liberal members of the Senate.

"The only thing I've seen Donald Trump do when it comes to U.S. trade policy is run his mouth and line his pockets," Brown said.