PHILADELPHIA — Presidential candidate Hillary Clinton told the Democratic National Convention on Thursday that Americans face challenges at home and abroad that require steady leadership in the White House.

In the biggest speech of her more than 25-year career in the public eye, Clinton sounded the themes that will propel her campaign against Republican Donald Trump in the Nov. 8 election.

“America is once again at a moment of reckoning. Powerful forces are threatening to pull us apart. Bonds of trust and respect are fraying,” Clinton said in accepting the Democratic nomination.

“We are clear-eyed about what our country is up against. But we are not afraid. We will rise to the challenge, just as we always have.”

Clinton said her “primary mission” will be 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.

“No wonder people are anxious and looking for reassurance — looking for steady leadership,” she said.

As she prepared to deliver her speech, people familiar with the matter said the FBI is investigating a cyberattack 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.

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, all party heavyweights who praised Clinton and cautioned that Trump would be dangerous and divisive.

It was a difficult and high-stakes task for the guarded Clinton, 68, known to be a more effective politician in small gatherings than on big stages.

In introducing her mother, daughter Chelsea Clinton said, “I’m here as a proud American, a proud Democrat, a proud mother and tonight in particular, a very, very proud daughter.”

Clinton, who is vying to be the first woman elected president in U.S. history, must make inroads with voters who find her untrustworthy or unlikable, as her favorability ratings in polls have hit all-time lows.

In a nod to her rival in the race for the nomination, she thanked U.S. Sen. Bernie Sanders of Vermont for a campaign that “inspired millions of Americans, particularly the young people who threw their hearts and souls into our primary.”

“You’ve put economic and social justice issues front and center, where they belong,” she said as Sanders listened from the audience. “And to all of your supporters here and around the country: I want you to know, I’ve heard you. Your cause is our cause. Our country needs your ideas, energy, and passion. That’s the only way we can turn our progressive platform into real change for America. We wrote it together — now let’s go out there and make it happen together.”

Of opponent Trump, 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. … He wants us to fear the future and fear each other.

“Well, a great Democratic President, Franklin Delano Roosevelt, came up with the perfect rebuke to Trump more than 80 years ago, during a much more perilous time:

‘The only thing we have to fear is fear itself,’” she said to thunderous applause from the crowd.

Trump, a 70-year-old New York businessman 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 convention by people who have 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 in Philadelphia, it sounded at times more like a traditional Republican convention than a Democratic one. During retired Gen. 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, a former reality TV star, 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. Sen. 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.