Billionaire Mark Cuban, owner of the NBA's Dallas Mavericks, said he is considering a 2020 presidential bid.
Cuban said if he runs, it would be as a Republican - setting up a possible primary challenge to President Trump.
The two billionaires traded barbs throughout the 2016 campaign, as Cuban supported Hillary Clinton - campaigning for her in his hometown of Pittsburgh.
Carlson asked Cuban what he would do about the declining number of highly wealthy folks in the country - saying that there are 200 fewer billionaires than in 2008.
Cuban said that, instead of Trumpian tax reform, he would support a decrease in the payroll tax for hourly workers, which would give them more take home pay.
As for how to pay for the plan, Cuban said he would look for ways technology could reduce the cost of other entitlements.
Carlson asked about the flood of low-wage workers into the country from Mexico and how it affects the economy.
Cuban said he understood both sides of the immigration argument in that respect - those on the right that see the problem as taking jobs from poorer Americans, and those on the left who point to the humanity issue.
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