UPDATE: Oct. 2 ― Amazon announced Tuesday that it would raise pay for all its employees to $15 per hour. CEO Jeff Bezos said in a release the company had listened to its critics.

Previously:

WASHINGTON ― The nation’s second-largest employer is raising wages in response to outside pressure and advocacy from its workforce, according to Sen. Bernie Sanders (I-Vt.).

For several weeks Sanders has been criticizing Amazon for low pay at its warehouses, even introducing legislation that would tax the company for what its workers receive in food stamp and Medicaid benefits.

In August, Sanders solicited testimonials from Amazon warehouse workers about low pay, which he showcased on his website and used to promote his legislation. Workers in several Amazon facilities told The Washington Post last week that they had received raises.

Sanders declined to take responsibility for the change, saying it was the workers who deserved credit for the raises.

“I think the workers have stood up and fought back,” he told HuffPost. “What we have done is call attention to the fact that it is a disgrace that the wealthiest person in this country and in this world are paying wages so low that workers are forced to go on food stamps and Medicaid.”

Amazon CEO Jff Bezos is worth more than $160 billion, making him the wealthiest person in the world, according to Forbes. Sanders titled his legislation ― which is a messaging bill that has little support and no chance of becoming law ― the Stop BEZOS Act. The purpose of the legislation is to shame the company for paying some of its workers so little they are poor enough to qualify for welfare benefits.

“I think the pressure is building not only on Bezos and Amazon but every other employer in America: Pay your workers a living wage, at least 15 bucks an hour,” Sanders said.

With more than half a million workers, only Walmart is a larger employer in the United States. The median Amazon employee makes $28,446 annually, according to the company’s filings with the Securities and Exchange Commission. Excluding part-timers and workers in other countries brings the median above $34,000, the firm has said.

The company’s “fulfillment center” employees pack the boxes that arrive on consumers’ doorsteps. Amazon has added more than 130,000 jobs in the past year, according to spokeswoman Lindsay Campbell.

“These are good jobs with highly competitive pay and full benefits,” Campbell said. “In the U.S., the average hourly wage for a full-time associate in our fulfillment centers, including cash, stock and incentive bonuses, is over $15/hour before overtime.”

The company has also said that raises workers have recently received were routine and not a response to outside pressure. (Low unemployment, at least theoretically, should also be putting upward pressure on wages, as there should be fewer workers desperate for jobs.)

One Amazon worker at a fulfillment center in Orlando ― whose contact information Sanders’ office provided to HuffPost ― said he thought his 50-cent raise he received had something to do with the pressure. The Orlando facility had just opened so he didn’t understand why the company would already be adjusting wages for workers who’d only been on the job a few weeks.

The worker said his pay increased from $11.25 per hour to $11.50. He likes his job, he said, but resented the company’s claim in an all-hands meeting a few weeks ago that factoring in stock awards means his hourly pay is actually $15.

“I knew it was a low-wage job when I took it,” he said. “Don’t piss on my leg and call it rain.”

HuffPost readers: Do you work in an Amazon fulfillment center? Tell us about it ― email arthur@huffpost.com. Please include your phone number if you’re willing to be interviewed.