Action News was there as Harris' motorcade arrived in Center City on Monday, making its way down 17th Street near Rittenhouse Square.
Trump is expected to arrive Tuesday for the highly-anticipated debate at the National Constitution Center.
Ahead of the must-watch event, Action News talked about potential debate strategies with Villanova University Political Science Professor David Barrett.
READ | Harris-Trump ABC News presidential debate: How to watch, what to know
He believes Trump's approach should focus on tying Harris to the economy and the lingering issues along the southern border.
"If you can sort of marginalize her candidacy by issues-oriented attacks, then I think that can go well for him," Barrett explained.
The professor said if he were advising Harris, he would encourage her to remain positive, even if Trump launches personal attacks.
"Focus on what she sees as the strength of her candidacy and doing it in a way that sort of gives off optimism and the sense of joy and focus on the future," he says.
Harris said in an interview that aired Monday that she expects Trump to lie during the ABC News presidential debate.
While Harris' strategy has been focused on establishing her presence and redefining herself for voters, she now plans to prioritize attacking Trump's record and getting under his skin during the debate.
Meanwhile, the Trump campaign and surrogates continued to insinuate on Monday that the former president's strategy at the debate will be to tie Harris to what they say are her policy failures and "disasters" as a leader of the Biden-Harris administration.
Barrett told Action News that, historically, presidential debates have rarely done much to move the needle of public opinion.
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Despite this, he says this debate might be one of the exceptions, especially if either candidate performs exceptionally poorly.
Action News asked people around Rittenhouse Square how they expected the debate to go.
"Harris will probably try to bring out the worst in Trump. There is a decent chance that he'll indulge her in that, but that does not seem to fundamentally move public opinion," said Adam Scales.
"I think there's a lot going on in the world right now. I think economically, politically, spiritually, people need directions so it'll be interesting to see," added Laura Rahauser.
'The ABC News Presidential Debate | Race for the White House' will air September 10 at 9 p.m. It will air on ABC and stream on 24/7 streaming network ABC News Live, Disney+, and Hulu.
ABC News contributed to this report.