PHILADELPHIA (AP) — Kamala Harris said Sunday that “no one can sit on the sidelines” in this year’s presidential election, capping a day of campaigning across the largest city in the crucial battleground state of Pennsylvania.

Watch Harris’ remarks in the player above.

“We are focused on the future and we are focused on the needs of the American people,” Harris said, “as opposed to Donald Trump, who spends full time looking in the mirror focused on himself.”

Speaking at a city recreation center, the Democratic vice president singled out young voters, praising them for being “rightly impatient for change,” and told the audience that “there is too much at stake” in the campaign.

“We must not wake up the day after the election and have any regret about what we could have done in these next nine days,” Harris said.

Mark Ruffalo and Don Cheadle, two actors who starred in Marvel’s “Avengers” movies, were at the rally. Harris reminded the crowd that Pennsylvania’s deadline for early voting is Tuesday, telling them to “get it done tomorrow if you can.”

Energizing voters in Philadelphia, a traditional Democratic stronghold, is crucial for Harris’ chances of beating Republican nominee Donald Trump. If turnout falls short here, she’ll struggle to overcome Trump’s advantages in Pennsylvania’s rural areas.

WATCH: On campaign blitz in Philadelphia, Harris says U.S. is ‘determined to turn the page’ on hate and division

“Philadelphia is a very important part of our path to victory,” Harris told reporters. “It’s the reason I have been spending time here. But I’m feeling very optimistic about the enthusiasm.”

Kenny Payne, 62, said Harris is going to win and “it won’t be close.” The Democratic voter said he plays golf with a group of Republicans who say they won’t vote for Trump again.

“I think we’ll all be in bed by midnight,” he said outside the recreation center where Harris spoke.

Patrick Boe, 46, said he was confident about the city’s enthusiasm for Harris, but he acknowledged that his view may be skewed.

“I’m in a bubble here,” Boe said.

Randyll Butler, a youth basketball coach who introduced Harris, said the election was in the “fourth quarter.”

“We cannot get tired,” she said. “We cannot get complacent.”

Harris and Tim Walz, the Minnesota governor who is her running mate, are expected to visit all seven battleground states in the coming days, part of a final blitz before the election.

WATCH: Walz gives remarks on reproductive rights at campaign event in Las Vegas

While Harris was in Philadelphia on Sunday, Walz was campaigning in Las Vegas. On Monday, Walz will visit Manitowoc and Waukesha, Wisconsin, before joining Harris for a rally in Ann Arbor, Michigan, where the singer Maggie Rogers is scheduled to perform.

Harris will be in the nation’s capital on Tuesday to deliver what her campaign calls her “closing argument” in a speech from the Ellipse, a grassy space near the White House. It’s the same place where Trump spoke on Jan. 6, 2021, when the Republican called on his supporters to march on the Capitol.

More campaign stops are scheduled in Georgia, North Carolina, Pennsylvania, Wisconsin, Nevada and Arizona.

Megerian reported from Washington.