Washington (CNN) About 40 contracted workers from the United States Senate walked off their jobs Wednesday morning and joined more than 1,000 labor activists at a rally calling on President Barack Obama and Congress to require federal contractors to pay their workers more.

The Senate workers -- employed at the upper chamber's cafeteria, on janitorial duty and in other food service jobs -- along with other federal contracted employees, are calling on the President to sign a "Model Employer Executive Order" that would give federal contracting preferences to companies that can pay their workers $15 an hour.

The Senate cafeteria, which keeps busy serving dishes likes it famous U.S. Senate bean soup on the Hill, is one of many federally contracted institutions in Washington.

Paco Fabian, a spokesperson for Good Jobs Nation -- one of the groups organizing the event -- confirmed that 600 of the workers were federally contracted employees, and that the Senate workers were galvanized by workers from the Capitol Visitors Center, who participated in a similar strike last November.

In February, Obama issued an executive order requiring that federally contracted employees are paid at last $10.10 an hour, but workers at the Capital, the Pentagon, the Smithsonian and other federal institutions say they are focused on earning a wage that allows them to have financial security and provide for their families.

Bertrand Olotara -- a cook at the U.S. Senate cafeteria -- published an op-ed in the British newspaper The Guardian Wednesday, saying that he joined the rally to tell members of Congress, the President and 2016 presidential hopefuls to stand up for a living wage.

"I am walking off my job because I want the presidential hopefuls to know that I live in poverty," he wrote.

The rally was joined by outspoken Sen. Bernie Sanders, a Vermont independent, and members of the Congressional Progressive Caucus, who joined in the call to increase wages for federally contracted workers.

"What we are saying today is pretty simply, that the taxpayers of this country want to make sure that when government contracts are made, those employers who get those contracts pay workers a living wage," Sanders told the crowd. "A great nation will not survive, in my view, when so few have so much and so many have so little."

Compass Group, a British-based catering company, confirmed that their subsidiary -- New York based Restaurant Associates -- contracts workers for the Senate cafeteria, but would not comment on the actions or demands of Olotara and other employees.

"(Restaurant Associates) takes pride in paying above market competitive wages, and while we're unable to comment on personal information for any one associate, RA can confirm that its contracts with the United States Senate and the Capitol Visitors Center are in full compliance with the ... wage and benefits provisions within the McNamara-O'Hara Service Contract Act (SCA)," said Cheryl Queen, vice president of Compass Groups USA, in a statement to CNN.