"Walmart is one of the nation's largest and worst employers – low wages, unreliable hours, few benefits, discrimination against women, and anti-union," said former Clinton Labor Secretary Robert Reich in a Facebook posting.
In a post entitled "Department of Ill-Advised Photo Opportunities," Reich asked: "What numbskull in the White House arranged this?"
Pam Ramos, who has worked at Mountain View, Calif., Walmart for four years, said that "when I heard President Obama was visiting my store, I wanted to tell him what income inequality really looks like – right here working at a company that made $17 billion last year."
In an op-ed for Salon, Ramos said she brings home about $400 every two weeks, and "that's not enough to pay for bills, gas and food. All I can afford to eat for lunch is a cup of coffee and a bag of potato chips."
Walmart says its wages and benefits are competitive in the retail industry.
White House officials said Walmart on Friday will commit to double the number of on-site solar energy projects at its U.S. facilities. Solar power, energy efficiency and renewable energy are topics of Obama's speech.
"The Walmart commitment is a significant commitment, and that's one of the reasons the president is going to be there," said Dan Utech, special assistant to Obama for energy and climate change.