Vice President Harris on Thursday was joined by businessman Mark Cuban on the campaign trail in Wisconsin, getting a boost from a high-profile surrogate as she highlighted her economic agenda.

Cuban and Harris greeted students at a business class at the University of Wisconsin-Milwaukee, the first of three planned stops for the vice president in the Badger State during the day.

The two visited a workspace at the school’s entrepreneurship center, which hosts a “Shark Tank” type competition for students to get funding for business ideas. Cuban was one of the original investors featured on ABC’s “Shark Tank.”

The event was closed to the press, with Harris delivering a statement on developments in the Middle East after the meetings with students.

Cuban also joined Harris for a campaign stop later Thursday in La Crosse before the vice president continued on to an event in Green Bay.

“You know, in my career I've learned a lot about business, including how tariffs work. Now let me just ask you a question, do you all know anyone who doesn’t know how tariffs work? All right I’ll give you a hint—that other guy,” Cuban said on stage, hitting former President Trump over his plans to impose tariffs on all imports.

“This man has so little understanding of tariffs, he thinks that China pays for them. This is the same guy who also thought that Mexico would pay for the wall,” Cuban added.

The billionaire businessman will campaign in the coming days for Harris in the swing states of Arizona and Michigan, the Harris campaign said. He has recently appeared on podcasts and television to stump for Harris and argue that her plans would be better for the business community than those of former President Trump.

“I mean, there’s really no good reason to vote for Donald Trump as the business candidate. In doing business, whether you’re a small company or a very large company, you want stability. You don’t want to wake up one morning as the CEO of John Deere and find out all of a sudden you have got a 200 percent tariff,” Cuban said during a recent media appearance, referencing a threat from Trump against the Illinois-based company.

The Harris campaign is hopeful that Cuban’s presence on the trail can help appeal to voters concerned about the economy, and to male voters in particular. Cuban is the former principal owner of the Dallas Mavericks and still owns a minority stake in the team.

Harris has for weeks outlined what she calls an “opportunity economy” agenda, calling for an increase in the housing supply, a crackdown on price gouging and an expanded child tax credit. Earlier this week she unveiled an economic agenda aimed specifically at bolstering the standing of Black men.

Trump’s economic proposals have included extending the 2017 tax cuts he signed into law, slashing the corporate tax rate further and eliminating taxes on Social Security, overtime and tipped wages.

Trump has also been adamant that he would impose wide-ranging tariffs on all imports into the United States and on companies who outsource their manufacturing overseas. The former president has repeatedly dismissed a slew of experts and studies that indicate his tariffs would increase costs for consumers and spark a trade war.

Updated at 4:51 p.m.