Democratic presidential candidate Sen. Elizabeth Warren's wealth tax would not generate enough money to make a dent in income inequality, said David Rubenstein, the billionaire co-founder of private equity powerhouse The Carlyle Group.
"I don't think all of a sudden a wealth tax, for example, would solve all of our society's problems, if one could ever actually be implemented," Rubenstein told CNBC's Leslie Picker on Tuesday from the Greenwich Economic Forum.
"If you tax the upper income, there aren't enough of those people to really make a wealth distribution effect that's going to be significant. There just aren't enough highly wealthy people," he added.
The Warren campaign was not immediately available to respond to CNBC's request for comment on Rubenstein's remarks.
The progressive Warren — running second in the Real Clear Politics national polling average — is proposing a 2% tax on household net worth above $50 million and a 6% tax on net worth over $1 billion. That, along with changing how investment gains are taxed for the top 1 percent of households, would generate more than $3 trillion over 10 years according to analysis from the New York Times.
Sen. Bernie Sanders, a democratic socialist, also supports a wealth tax. Joe Biden, the centrist former vice president who remains the frontrunner, has vowed to repeal tax cuts for the wealthy but has not called for a wealth tax.