Democrat Hillary Clinton took her newly energized campaign to become America's first woman president on the road on Friday to states in the "Rust Belt" that might decide the fate of the Nov. 8 election.
After presenting an upbeat view of the country in her keynote address to the Democratic convention on Thursday night, the former secretary of state launched a campaign tour of Ohio and Pennsylvania, two heartland states hit by the decline in U.S. manufacturing.
Clinton is likely to face a tough challenge in such states from Republican nominee Donald Trump, a New York businessman who is trying to win white working-class voters with rhetoric against free trade and illegal immigration.
"There is no doubt in my mind that every election in our democracy is important in its own way but I can't think of an election that is more important, certainly in my lifetime," Clinton told a rally in Philadelphia on Friday.
"And it's not so much that I'm on the ticket it's because of the stark choice that's posed to America in this election," she added.
In the biggest speech of her quarter century in politics, Clinton formally accepted the Democratic presidential nomination on Thursday at the convention in Philadelphia. She cast herself as a steady leader at a "moment of reckoning" for the country, and contrasted her character with what she described as Trump's dangerous and volatile temperament.
Clinton and her vice presidential running mate, U.S. Senator Tim Kaine of Virginia, addressed a crowd of more than 5,000 people at Temple University near downtown Philadelphia, before heading out on their three-day bus tour. Clinton reprised themes from her Thursday night speech.
Opinion polls show a potentially tight race in Ohio and Pennsylvania, both of which were won by President Barack Obama in the 2012 election.
Clinton and Trump are essentially tied in Ohio, where the Republicans held their convention last week, according to an average of polls by RealClearPolitics. Clinton has a lead of 4.4 percentage points in Pennsylvania, the website's average of recent polls showed.
Ohio and to a lesser extent Pennsylvania are among a handful of competitive states that are traditionally viewed as decisive in U.S. presidential elections, since they do not lean heavily either Democratic or Republican.
Nationally, opinion polls show Trump moving into a slight lead after receiving his party's nomination at the convention in Cleveland. Clinton is likely to get a similar boost after the Democratic convention, where she was lauded by Obama and other senior Democrats as a tough fighter with a long-held passion for helping the underprivileged.
TV viewership lower for Clinton
Clinton, a former first lady and U.S. senator, promised in her speech on Thursday to make the United States a country that works for everyone if she is elected.
"We are clear-eyed about what our country is up against. But we are not afraid," she said. Clinton, 68, portrayed Trump, 70, as a threat to the country, saying "a man you can bait with a tweet is not a man we can trust with nuclear weapons."
Trump sent out a flurry of comments on Twitter on Friday morning, lambasting media coverage of the speech as "a joke," calling the address "very long and very boring" and accusing Clinton of wanting to shut down "coal mines, steel plants and any other remaining manufacturing."
He will campaign in another swing state, Colorado, on Friday and is scheduled to visit Ohio next week.
The U.S. television audience for Clinton's acceptance speech appeared smaller than the viewership of Trump's address a week earlier, according to preliminary ratings data released on Friday.
An estimated 27.8 million people watched Clinton across six broadcast and cable networks, early Nielsen data showed. Trump had pulled in roughly 30 million from those networks. Updated figures were expected later on Friday.
Economic issues will be crucial as the White House campaign enters its final three-month stretch. The U.S. economy grew by only 1.2 percent in the second quarter, far less than expected, the Commerce Department said on Friday.
During the Rust Belt trip, Clinton will detail her pledge to raise wages and to create jobs by unveiling a major infrastructure package within the first 100 days of her presidency, and encouraging companies to invest in workers.
The start of the Democratic convention was overshadowed by the resignation of Democratic National Committee Chairwoman Debbie Wasserman Schultz who quit over leaked emails showing party officials favored Clinton over her primary rival Bernie Sanders, a U.S. senator from Vermont.
Cyber security experts and U.S. officials said on Monday there was evidence that Russia engineered the release of the emails in order to influence the election. The Kremlin has denied the accusations.
Another hack came to light on Thursday, when four people familiar with the matter told Reuters the FBI is investigating a cyber attack against the Democratic Congressional Campaign Committee, which raises money for Democrats running for the U.S. House of Representatives. The DCCC confirmed on Friday that it had been the target of a cyber security incident.