"In other words, the taxpayers of this country would no longer be subsidizing the wealthiest people in this country who are paying their workers inadequate wages," Sanders said at a news conference announcing the bill. "Despite low unemployment, we end up having tens of millions of Americans working at wages that are just so low that they can't adequately take care of their families."

The proposed legislation comes one day after Amazon reached $1 trillion in market cap, a milestone that reinforces its position as one of the world's wealthiest companies. The only publicly-traded U.S. company valued higher is Apple, with a market cap of $1.1 trillion. (Bezos, who founded Amazon, is the world's wealthiest person and owns The Washington Post.)

"Amazon is worth $1 TRILLION," Sanders tweeted Tuesday. "Thousands of Amazon workers have to rely on food stamps, Medicaid and public housing to survive. That is what a rigged economy looks like."

Amazon has fired back against Sanders and his claims that thousands of Amazon employees rely on federal benefits to make ends meet. Those figures are “inaccurate and misleading,” the company said last week, because they include temporary workers as well as those who choose to work part time.

The value of Amazon's stock has more than doubled in the past year, causing Bezos's net worth to skyrocket 69 percent to $168 billion, according to the Bloomberg Billionaires Index. The median Amazon worker, meanwhile, was paid $28,446 last year, according to company filings.

The bill follows similar legislation introduced in Congress last summer by Rep. Ro Khanna (D-Calif.). The Corporate Responsibility and Taxpayer Protection Act currently has nine co-sponsors, including Democratic Reps. Barbara Lee of California, Jamie B. Raskin of Maryland and Eleanor Holmes Norton of the District.

"All this legislation is saying, is: Taxpayers shouldn't be responsible for paying the expenses of workers employed by multibillion-dollar companies," Khanna said. "The basic premise of the American Dream is that if you work hard and you work for a company that's doing well, you should earn enough to support your family. Instead, we have an absurd situation where companies with a trillion dollars in market cap — the wealthiest in the world — with employees who don't make enough to support the basic needs of themselves and their families."

But some economists said they worried such measures may backfire by creating incentives for companies to avoid hiring workers who may be likely to collect federal benefits.

"I'm afraid this is a solution that vilifies benefit recipients," said Jared Bernstein, senior fellow at the Center on Budget and Policy Priorities, and former economic adviser to Vice President Joseph Biden. "It's not hard to imagine that employers would be wary of hiring someone who they think -- rightly or wrongly -- would invoke the tax."

Sanders said his office had heard from "many hundreds" of current and former Amazon workers who have had to rely on the Supplemental Nutrition Assistance Program, Medicaid and other government programs to cover their families' basic needs. There is no official measure of a "living wage," but the federal poverty level for a family of four is $24,600.

Denise Bennett, a former Amazon worker in Tennessee, said she made $11 an hour as a full-time employee but had to rely on SNAP benefits to make ends meet. She and her three children also lived with her parents while she was working at Amazon because, as she told Sanders's office, "I could not afford to find a safe location for my family."