Entrepreneur Mark Cuban speaks at a campaign event for US Vice President Democratic presidential nominee Kamala Harris at the University Wisconsin-La Crosse.Craig Lassig / AFPMark Cuban on CNBC said the presidential campaign is now a fight between Kamala Harris and Elon Musk.Cuban said the outcome of the election hinges on voter turnout, which Musk has made a priority.Musk is offering cash incentives to register voters and a $1 million lottery to swing state voters.Billionaire businessman Mark Cuban on Monday said the presidential campaign has become a battle between Vice President Kamala Harris and Tesla CEO Elon Musk rather than Donald Trump.Speaking on CNBC's "Squawk Box," Cuban said Harris is fighting against Musk, a campaign surrogate for Trump, as much as she is against her political rival, saying that the outcome of this year's election will hinge on voter turnout — an issue Musk has made a priority in recent weeks."Really it comes down to 'get out the vote,'" Cuban, who has campaigned on behalf of Harris, said of the election.