Mark Cuban has been one of the Harris campaign's most visible outside surrogates in recent months.

Now he's making it official.

The billionaire businessman will make a series of formal campaign appearances for Kamala Harris, starting with stops alongside the vice president later today, a campaign aide told Yahoo Finance exclusively.

It's a move that comes as the Harris campaign ramps up its efforts to reach young men and further capitalize on the “Shark Tank” star's popularity in the financial and sports worlds.

The first stop today will be alongside the Vice President in Milwaukee and La Crosse, Wisconsin.

Then the former majority owner of the Dallas Mavericks (he still holds a minority stake in the NBA team) will headline a town hall in Phoenix, Arizona on Saturday. He will also make a stop in Grand Rapids, Michigan on Sunday with second gentleman Douglas Emhoff.

The cross-country Cuban movement comes at a time when Donald Trump's billionaire supporters are becoming increasingly important in this stretch of the campaign, with the end of voting now less than 20 days away.

Tesla (TSLA) CEO Elon Musk is currently in Pennsylvania for a series of conversations with voters on Trump's behalf. Campaign finance filings Tuesday also revealed that Musk donated nearly $75 million to his Trump-supporting super PAC in the most recent quarter.

Cuban's role as Harris' voice on the economy

The Harris campaign's upcoming move is an escalation of Cuba's prominence on Harris' behalf, but it is far from the first contact between him and the campaign.

In recent months, he has appeared on numerous podcasts and national media outlets to voice his support for her, and he has also repeatedly criticized Trump on issues such as trade and taxes.

Cuban has also become a prominent pro-Harris voice on X, formerly Twitter, where he often interacts with Musk, who owns the platform.

In September, he also participated in a call with reporters on behalf of the campaign, where he discussed how he had regular conversations with aides and, at the end of the process, “I get back a serious, well-thought-out answer; “That’s the opposite of what Donald Trump is doing.”

“He doesn’t think these things through,” he added of Trump, calling some of his ideas “often ridiculous, if not crazy.”

Cuban also often speaks about health care in his defense of Harris, having founded the Mark Cuban Cost Plus Drug Company in 2022, which aimed to lower generic drug prices.

Cuban's new role also comes as the Harris-Walz campaign increases its advertising spending on male-dominated platforms, including major sporting events and video game websites.

The story continues

The move also comes as Trump himself ramps up his own economic rhetoric, particularly on the trade issue.

At an event at the Economic Club of Chicago this week, he suggested he wanted “the highest tariff in history” and floated the idea of ​​blanket tariffs of up to 50% to force companies to relocate immediately.

Ben Werschkul is a Washington correspondent for Yahoo Finance.

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