In an email sent out Wednesday to supporters, Sen. Bernie Sanders called out members of the billionaire class for enriching themselves at others’ expense. In the same gesture, he called on Americans to push back against their exploitation of the power their economic positions afford them—and of the labor force that sustains it.

And Sanders named names. Specifically, the Vermont senator lashed out at Amazon CEO Jeff Bezos, who has recently made headlines about his skyrocketing executive compensation—in 10 seconds, Bezos makes more than the median annual salary for Amazon employees—as well as about Bezos’ comments about looking to space for new ways to spend his vast wealth.

Echoing themes picked up by other commentators, Sanders pointed out that there are many more necessary and obvious places where Bezos could channel his funds. “Instead of attempting to explore Mars or go to the moon,” Sanders wrote, “how about Jeff Bezos pays his workers a living wage?”

This wasn’t the first time Bezos has inspired Sanders to vent against what he has characterized, in a refrain he pushed during his 2016 presidential campaign, as a “rigged economy.” Wednesday’s blast made explicit how much Amazon’s inadequate wages wind up costing the rest of the country in the long run. As “thousands of Amazon employees are forced to rely on food stamps, Medicaid and public housing because their wages are too low,” Sanders wrote, taxpayers are forced to pick up the bill. “I don’t believe that ordinary Americans should be subsidizing the wealthiest person in the world because he pays his employees inadequate wages,” he said.

Though Bezos didn’t respond to the finer points (or any points, for that matter) of the legislator’s critique, Truthdig Editor in Chief Robert Scheer backed Sanders up:

The entire statement is a powerful indictment of wealth inequality and the exploitation of workers from one of our most respected political leaders. Most of us, myself included, underestimate the unprecedented concentration of power in a few hands in recent years. It is a much ignored labor story of rank exploitation of workers that gives the lie to holding immigrant labor responsible.

Read Sanders’ petition in full below: