An unusual public spat between Amazon.com Inc. and Sen. Bernie Sanders over workers’ wages escalated Wednesday as the Vermont independent introduced a bill aimed at taxing big companies whose employees rely on federal benefits to make ends meet.

Mr. Sanders specifically targeted Amazon founder and leader Jeff Bezos, contrasting his vast personal wealth with the compensation of the companies’ lowest-paid workers.

The senator, speaking at a press conference introducing the bill, noted Mr. Bezos “could play a profound role” in altering the national discourse regarding pay by guaranteeing no Amazon worker receives less than a living wage, or enough to cover rent, food and other basic necessities.

“This would not only improve lives for thousands of people at Amazon; it would send a message to every corporation in America that that’s where we should be going as a nation,” Mr. Sanders said.

The legislation is aimed at ending what Mr. Sanders has said is middle-class taxpayers’ subsidization of large, profitable companies owned by billionaires. The bill, co-sponsored by Rep. Ro Khanna (D., Calif.), would tax companies with 500 or more employees an amount equal to federal benefits received by their low-wage workers, effectively forcing them to pay more one way or another.