Presidential hopeful Bernie Sanders campaigned for income equality outside and inside the U.S. Capitol building Wednesday, rallying striking workers in a park across the street from Congress and introducing a bill in the Senate to hike the federal minimum wage to $15 an hour.

“The current federal minimum wage is a starvation wage. It’s got to be raised to a living wage,” Sanders told a crowd mixed with federal contract workers, fast-food employees, and labor activists. “I think that if you work 40 hours a week, you have a right not to be living in poverty.”

The current federal minimum wage is $7.25 per hour. Sanders, a Vermont independent who’s seeking the Democratic presidential nomination, said it’s particularly appalling that the United States government is among the nation’s largest employers of low-wage workers.

“It’s a national disgrace that millions of full-time workers are living in poverty and millions more are forced to work two or three jobs just to pay their bills,” Sanders said. “In the year 2015, a job must lift workers out of poverty, not keep them in it.”

He urged President Barack Obama to sign an executive order “so that every federal contract worker in this country is paid a living wage, good benefits, and the right to join a union.”

Sanders is making income equality a centerpiece of his presidential campaign. He introduced a Senate bill Wednesday that would raise the minimum wage to $10 per hour by 2020 and close a loophole that he says allows employers to pay tipped workers as little as $2.13 per hour.

Reps. Keith Ellison, D-Minn., Raul Grijalva, D-Ariz., and Sheila Jackson Lee, D-Texas, introduced a similar measure in the House of Representatives. The prospects of the bills getting through a Republican-controlled House and Senate are slim.

Former Secretary of State Hillary Clinton, the Democratic presidential frontrunner, supports raising the minimum wage, but has declined to say what amount. Former Maryland Gov. Martin O’Malley supports a $15 minimum wage.

Clinton, responding to a BuzzFeed reporter’s question last week, said she supports “the local efforts that are going on that are making it possible for people working in certain localities to actually earn 15.”

She added: “I think part of the reason that the Congress and very strong Democratic supporters of increasing the minimum wage are trying to debate and determine what’s the national floor is because there are different economic environments. And what you can do in L.A. or in New York may not work in other places.”

McClatchy’s Anita Kumar contributed to this report.