At one point, he supported the presidential aspirations of Donald Trump, a fellow reality TV star and businessman. But now Mark Cuban — perhaps best known for his longtime ownership of the Dallas Mavericks and his perch as a “Shark Tank” shark — has taken on a surprising new role. He is a prolific and vocal supporter of Kamala Harris. Especially when it comes to his view of what a Harris administration would mean for the economy. So, as we enter the homestretch toward Election Day, today on The Run-Up: A conversation with Kamala Harris’s most surprising surrogate.