Trump is now weighing in on Harris' plans to visit the southern border this Friday in Arizona, labelling the visit as "political" and accusing her of attempting to "con the public" of her border record.

"After almost four years, Border Czar Kamala Harris has decided, for political reasons, that it’s time for her to go to our broken Southern Border. What a disgrace that she waited so long," Trump wrote on his social media, repeating his disparaging rhetoric on migrants.

While Harris has been to the southern border, the trip marks her first visit since lauched her campaign at the end of July.

Trump has made immigration central to his 2024 campaign, pledging mass deportations and a border shutdown among other hard-line policies. He visited the border last month, the same day Harris formally accepted the Democratic nomination for president.

ABC News' Soorin Kim, Lalee Ibssa and Kelsey Walsh

Vice President Harris is planning to visit the southern border during her visit to Arizona on Friday, according to a source familiar.

This would be Harris' first visit to the southern border since she jumped to the top of the ticket at the end of July.

Immigration has been a big issue in the 2024 race, with Donald Trump and Republicans inaccurately calling Harris the "border czar" and blaming her for the border crisis. Harris, in turn, argues that Trump and Republicans are at fault for killing the bipartisan border bill earlier this year.

Harris has overseen the Biden administration's efforts to address the root causes of migration as vice president, and visited the border in 2021, after she came under fire for not having done so.

ABC News' Molly Nagle

Trump is expected to return to Butler, Pennsylvania, the city of his first assassination attempt, next Saturday for a rally, according to multiple sources familiar with his plans.

The rally is scheduled for Oct. 5.

Trump has long promised to return to Butler to honor the victims who died at his July rally.

"I WILL BE GOING BACK TO BUTLER, PENNSYLVANIA, FOR A BIG AND BEAUTIFUL RALLY, HONORING THE SOUL OF OUR BELOVED FIREFIGHTING HERO, COREY, AND THOSE BRAVE PATRIOTS INJURED TWO WEEKS AGO. WHAT A DAY IT WILL BE — FIGHT, FIGHT, FIGHT! STAY TUNED FOR DETAILS," Trump wrote on his social media platform in July.

NBC News was first to report the news.

ABC News' Katherine Faulders, Lalee Ibssa, Kesley Walsh and Soorin Kim

Vice President Harris will not attend the Al Smith dinner next month in New York, breaking with tradition of major party nominees sharing laughs at the benefit dinner, and will instead be on the campaign trail, a campaign official confirmed to ABC News.

"She is going to be campaigning in a battleground state that day, and the campaign wants to maximize her time in the battlegrounds this close to the election," the official said.

The dinner, which benefits Catholic Charities, is scheduled for Oct. 17. It has become a traditional stop on the presidential campaign trail, with both the Republican and Democratic nominees attending and delivering remarks full of roasts. In recent years, both nominees attended the gala, including in 2008, 2012, 2016, and 2020. (The latter was virtual because of the COVID-19 pandemic.)

The official also added that Harris' team informed the dinner's organizers she would be absent, but was willing to attend in a later year as president.

ABC News' Fritz Farrow, Gabrielle Abdul-Hakim and Will McDuffie