Senator Elizabeth Warren on Wednesday rekindled her call for a tax on the wealth of the richest Americans, calling billionaire Amazon founder and space tourism magnate Jeff Bezos about his inability to pay his fair share.

Jeff Bezos speaks about his Blue Origins New Shepard flight into space during a press conference on July 20, 2021 in Van Horn, Texas.

Joe Raedle | Getty Images

“I want us to tax assets, but your assets are tied. It shouldn’t make a difference if you have real estate, if you have cash, or if you have a bazillion stocks of Amazon. Yes, Jeff Bezos, I’m looking at you, “the Massachusetts Democrat said in CNBC’s Squawk Box.

“Whatever your assets – diamonds, yachts, paintings – I think they should be taxed annually,” she added.

Bezos is the richest person in the world with a net worth of $ 207.7 billion, according to Forbes.

Amazon didn’t immediately respond to a CNBC request for comment on behalf of Bezos.

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A wealth tax, one of the most hotly debated tax proposals, is enjoying growing popularity among populist and progressive politicians as a means of tackling economic inequality.

During her 2020 presidential campaign, Warren proposed an annual “ultra-millionaire tax” of 2% on net worth over $ 50 million and 6% on assets over $ 1 billion. The proceeds of such a tax – $ 2.7 trillion over a decade according to the Wharton School – would have been used to improve health care, childcare, housing and education programs.

Warren mentioned Bezos several times during her interview, arguing that he and others wrongly avoided paying into the U.S. tax system thanks to low annual book revenues and loans for his most valuable asset – his Amazon stock.

“Jeff Bezos didn’t pay tax on his fortune,” she said. He is “worth a bazillion dollars. He paid no tax on all that wealth. … In fact, Jeff Bezos either paid no tax or paid 1% for many years.”

Their barbs at Bezos came a little over a week after the e-commerce tycoon shot to the edge of space with its space tourism company Blue Origin.

“For every Amazon customer out there and every Amazon employee, I thank you from the bottom of my heart. That is very much appreciated,” said Bezos after his flight.

The tourism market is a sliver of the space economy estimated at $ 420 billion.

The launch marked Blue Origin’s entry into the private space market, joining Richard Branson’s Virgin Galactic – its direct competitor in the suborbital tourism sector – and Elon Musk’s SpaceX.

In the interview, Warren also said that she was skeptical that Bitcoin would prove to be a reliable protection against inflation in the long run, a major reason some investors choose to own Bitcoin.