As promised, Senator Bernie Sanders introduced a bill Wednesday that would tax Amazon, Walmart WMT

Named the Stop Bad Employers by Zeroing Out Subsidies, or the Stop BEZOS Act after Amazon (AMZN) founder Jeff Bezos, Sanders' bill would levy a tax on large companies equal to the value of the public benefits that their workers receive. He argues that if employers paid a living wage, taxpayers would save $150 billion a year on the government assistance programs, including food stamps, Medicaid and public housing.

"We do not believe that taxpayers should have to expend huge sums of money subsidizing profitable corporations owned by some of the wealthiest people in this country. That's what a rigged economy is about," said Sanders, who introduced the bill with California Representative Ro Khanna, a Democrat.

The independent senator from Vermont recently asked Amazon workers to tell him about their work conditions. He shared a few examples from workers who said that they make only $11 an hour or $13.25 an hour, which isn't enough to live on.

Sanders also lashed out Wednesday at Burger King, McDonald's (MCD) and American Airlines (AAL) for paying wages so low that their workers have to sign up for government benefits.

Related: Amazon defends itself from Bernie Sanders' attacks

Amazon, however, called Sanders' assertions "inaccurate and misleading" in a blog post last week. The company says that Sanders' data for food stamp recipients includes people who only worked at Amazon for a short period of time or who chose to work part-time. The median US salary for full-time Amazon employees is $34,123, it says. Sanders' figure includes part-time employees and those who work globally.

It has invited the senator to tour one of its fulfillment centers, which is where many of Amazon's lower-paid employees work.

The company highlighted that its average hourly wage for a full-time fulfillment center employee is more than $15 an hour, including cash, stock and incentive bonuses, but before overtime. Amazon also noted that it offers health and disability insurance, as well as retirement savings plans, company stock, tuition payments and up to 20 weeks of paid leave. The company says it created more than 130,000 new jobs in the U.S. last year.

Amazon posted on Wednesday the positive responses that several employees sent to Sanders and shared with the company. They cited the fair pay, good benefits, supportive environment and opportunities for career advancement.

The other employers mentioned didn't immediately return requests for comment.

Related: Bernie Sanders is hosting a town hall for workers. Their CEOs are invited.

Sanders' legislation has also raised concerns with at least one prominent left-leaning organization.

The bill would create powerful incentives for employers to shy away from hiring low-income workers, who are more likely to qualify for Medicaid, food stamps or housing assistance, said a report from the Center on Budget and Policy Priorities. Also, it may lead some companies to pressure their employees not to sign up for benefits.

Plus, the legislation likely wouldn't do much to raise wages, the center said. Companies would have to raise wages for all workers in particular job categories, which would be more expensive than paying the new tax, the center said.

Sanders' campaign says they have added provisions to the bill to help prevent those things from happening, such as making it unlawful for a large employer to ask an employee whether or not they qualify for federal benefits.