Employment has become one of Amazon’s most potent political vulnerabilities as well as its most important political message. The shift to online shopping, led by Amazon, has forced many retailers like Toys “R” Us and Sears to shut down or lay off workers across the country. President Trump has criticized the company for hurting traditional retailers, and some lawmakers have called for the company to be broken up.

At the same time, jobs at Amazon’s warehouses and sorting centers have boomed. The company now employs about 575,000 people worldwide, up more than 50 percent in the past year, a fact Amazon frequently plays up.

But the pay of those workers has become a growing issue for activists, especially as the fortunes of Amazon and Mr. Bezos have skyrocketed. Amazon’s market capitalization passed $1 trillion last month, though it has since fallen slightly below that level. Mr. Bezos is now the richest person in the world, with a net worth of $165 billion, according to the Bloomberg Billionaires Index.

“I think they saw the writing on the wall. I think they saw the calculation that it was indefensible that a man whose wealth is over $150 billion be able to continue paying workers wages that are so low that they are forced to rely on federal benefits,” Senator Bernie Sanders of Vermont said in an interview after the announcement. “Smart people are willing to change course.”

Mr. Sanders and labor organizers have criticized the wages and conditions of Amazon’s work force. They have focused on employees at the company’s warehouses, and with the contract drivers who make last-mile deliveries. Some workers at the grocery chain Whole Foods, which Amazon bought last year, have recently begun a push to organize a union.