Sen. Bernie Sanders has introduced a bill in the Senate to raise the federal minimum wage to $15 an hour.

Sanders, a Vermont Independent who is running for the Democratic presidential nomination on a largely socialist platform, announced the legislation at an outdoor rally near the U.S. Capitol. He called the current federal minimum wage of $7.25 per hour "a starvation wage."

Sanders said his bill would also "close a loophole" that permits restaurants to pay tipped employees just $2.13 per hour.

"It is 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. The current federal minimum wage of $7.25 an hour is a starvation wage and must be raised to a living wage."

House Democratic lawmakers have introduced a similar wage increase bill in the House, but neither measure has much chance of passing because Republicans control both chambers and are largely opposed to a federal minimum wage hike.

Sanders also called on President Obama to increase the minimum wage to $15 for federal contract workers and enact regulations that would make it easier for federal contract workers to unionize.