Former President Barack Obama responded on Monday to the disparaging comments about Puerto Rico that were made by a comedian who opened for Donald Trump at his rally in New York City over the weekend.

“So, the man holds this big rally at Madison Square Garden, and the warm-up speakers were saying the most – were trotting out and peddling the most racist, sexist, bigoted stereotypes. One guy called Puerto Rico, quote, 'an island of garbage,'” Obama said at a rally in Philadelphia, Pennsylvania, which is home to one of the largest Puerto Rican populations in the U.S.

“These are fellow citizens he’s talking about. Here in Philadelphia, they are your neighbors. They’re your friends. They are your coworkers. Their kids go to school with your kids. These are Americans. They’re people -- and that is the reason why this election should not be close. It should be clear,” he added.

Joining Obama at Temple University's Liacouras Center in North Philadelphia were Bruce Springsteen and John Legend, both of whom performed as part of the When We Vote We Win concert series in support of Vice President Kamala Harris, with eight days to go until Election Day.

Vice President Kamala Harris joined Gov. Tim Walz on the trail for the first time since August in Ann Arbor, Michigan Monday, where she rallied voters ahead of Election Day.

During her stump speech, about a dozen pro-Palestinian protesters interrupted Harris, decrying Israel.

"Hey guys, I hear you on the subject of Gaza," Harris said.

"We all want this war to end as soon as possible and get the hostages out, and I will do everything in my power to make it so," Harris added.

Ann Arbor, located in Michigan's sixth district, was one of the two districts that gained an uncommitted delegate during Michigan's primary, in large part, because of its sizable community of college students.

The other district that gained an uncommitted delegate was the 12th, which included Detroit suburbs with large blocs of Arab-Americans.

-ABC News' Gabriella Abdul-Hakim

Minnesota Gov. Tim Walz delivered a focused message that aimed to rally young voters in the crowd as he stumped for Vice President Kamala Harris in Ann Arbor, Michigan, on Monday.

In an appearance near the University of Michigan campus, with a little over a week before Election Day, Walz delivered a short and thoughtful speech boosting his running mate's candidacy.

“Look, her first day -- from a prosecutor to a district attorney to the attorney general of California to a United States senator to the vice president -- Kamala Harris had that one client: the people," Walz said.

He also, at times, tapped into his "coach" persona. “Now we're moving this thing over the next eight days, an inch at a time, a yard at a time, one door at a time, one phone call at a time," Walz said. "[Because] one of those door knocks, and one of those interactions -- because one or two extra votes for precinct in the state of Michigan will make Kamala Harris the president the United States."

Walz acknowledged head-on the anxiety that young, first-time voters may be feeling during this election cycle.

“Here's the good news: If you're feeling any of that anxiety, any of that nervousness, any of that worry, we've got the solution for you. Get out there and vote for Kamala Harris. I know I did it last Wednesday with my son, who voted [for] the first time, and it works,” he said to the crowd of largely students.

It was Walz's first joint rally with Harris since their appearance in Milwaukee, Wisconsin, during the Democratic National Convention in August.

During a stop in Kalamazoo, Michigan, at Trak-Houz Bar & Grill where Vice President Kamala Harris and the state's governor, Gretchen Whitmer, were grabbing a beer, a hot mic caught Harris discussing that her campaign is struggling with male voters.

“So, everyone agrees that we need to move the ground with men,” Harris said. She goes on to look around at the cameras, saying, "Oh, we have microphones in here just listening to everything. I didn't realize that. We just told all the family secrets. S---," she said while laughing.

On the record, Harris flat-out rejects that she has any issues with male voters. ”It’s not what I see in terms of my rallies, in terms of the interactions I’m having with people in communities and on the ground,” Harris said at a campaign stop in Philadelphia last week.

"What I am seeing is in equal measure, men and women talking about their concerns about the future of our democracy, talking about the fact that they want a president who leads with optimism and takes on the challenges that we face, whether it be grocery prices or investing in small businesses or home ownership," Harris said at the time.

The vice president's campaign has notably been doing extensive outreach to male voters. The campaign announced on Sunday that they were focusing on outreach during NFL games, 3v3 games and Twitch streams to mobilize and activate fans. They also launched Athletes for Harris, co-chaired by Magic Johnson, and have placed ads on fantasy sports, sports betting and sports news sites in an effort to close the gap with male voters.