President Biden and Vice President Harris will hold a joint event in Maryland on Thursday, Aug. 15, according to the White House.

They will discuss "the progress they are making to lower costs for the American people," the White House said.

Meanwhile, ahead of visits this weekend to Arizona and Nevada, the Harris campaign is touting what it called its "historic ground game advantage" in the two battleground states.

In a memo, the campaign also notes the elevated importance in Arizona and Nevada of reproductive freedom, as abortion-related ballot measures will be in place in each state this fall.

"Vice President Kamala Harris and Governor Tim Walz's momentum across the battlegrounds is real and will be on full display in Arizona and Nevada, where we've built massive coordinated campaigns as Trump has almost no presence whatsoever," the memo read. "Our campaign will continue our work to reach the diverse voters who power our victories in the Southwest, highlighting the stakes of the race for reproductive rights and the Vice President's leadership to secure the border."

Former President Donald Trump is set to hold a campaign rally in Bozeman, Montana, on Friday.

Vice President Kamala Harris will not be joining former President Donald Trump on Fox News' debate stage on Sept. 4, a Harris campaign official told ABC News.

The official said Harris agreeing to future debates is contingent on Trump showing up and "keeping his word" to the Sept. 10 debate, hosted by ABC News.

Harris' campaign is willing to have conversations about future debates, but they must be scheduled after Sept. 10, according to the official.

Vice President Kamala Harris and Gov. Tim Walz gave remarks at a local United Auto Workers office in Wayne, Michigan, on Thursday, championing "the collective."

Walz praised Harris' leadership, saying, "She stands on the side of the American people and the American worker. She’s the one who took on the predators, the fraudsters, the transnational gangs," Walz said.

"And she’s the one that stands up against the billionaires and the corporate greed -- it’s who Kamala Harris is," he added.

Harris took the stage largely repeating her newly tested stump speech, letting the audience know her campaign is for everyone.

"We believe in the collective," Harris said. "We're not falling for these folks who are trying to divide us trying to separate us, trying to pull us apart. That's not where the strength lies," she added.

She ended her remarks by reminding the crowd of how many days were left until voting day and how much hard work was left to win the election.

"We've got 89 days to get this done. You know, the one thing about all of us is we like hard work. Hard work is good work," she said.

-ABC News' Gabriella Abdul-hakim

President Joe Biden said that he has confidence in Vice President Kamala Harris in her upcoming debate with former President Donald Trump.

Speaking to reporters on the tarmac of Joint Base Andrews Thursday, Biden assured he was undoubting of Harris while also making a dig at Trump.

"Yes, I am," Biden said of his confidence in Harris. "As long as he keeps talking," he added of Trump.

On Thursday, Trump agreed to join Harris on the debate stage hosted by ABC News on Sept. 10.