With scandal at the Department of Veterans Affairs still smoldering, first lady Michelle Obama today used her megaphone to deliver an impassioned call to action on veteran homelessness, a problem she declared a "moral outrage."

"Even one homeless veteran is a shame," she said at an East Room event sponsored by her Joining Forces initiative. "The fact that we have 58,000 is a moral outrage. We should all do more about it."

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Obama was launching the Mayors Challenge to End Veteran Homelessness, an effort that has drawn commitments from 77 mayors, four governors and four county officials to more aggressively reach out to homeless vets and connect them with available resources.

(Gary Cameron/Reuters)

"Tens of thousands of veterans who risked their lives for our country are living in a shelter or sleeping near a subway vent. We should be horrified," she said, "because that's not who we are as Americans.

"When a veteran comes home kissing the ground, it's unacceptable that he should sleep on it."

The White House, which in 2009 declared a goal of ending veterans' homelessness by 2016, says progress is being made but not quickly enough.

Homelessness has declined 24 percent among veterans in the past four years, studies show. Less than 1 percent of all U.S. veterans today are homeless. Veterans without a home make up just 12 percent of the overall homeless population in the United States, according to the National Coalition Against Homeless Veterans.

Chris Fuentes, an Iraq War veteran from Philadelphia, says she is one of the success stories.

"When I returned from active duty, my apartment and job were gone," Fuentes, 25, said. "At one point I found myself living in my car, while my daughter stayed with my mother. I was all over the place, jumping from place to place. I knew that if only I could have a roof over my head everything else would fall into place."

She applied for benefits through the Department of Housing and Urban Development and the VA, she said.

"Today thanks to these programs, we have a home again," Fuentes said. "These programs give veterans a second chance at life and allows them not to worry about where they'll lay their head at night."

Appearing with Obama at the event was acting VA Secretary Sloan Gibson, who has succeeded Eric Shinseki after he abruptly resigned last week amid a firestorm over secret wait lists and lengthy wait times for thousands of veterans seeking medical care.

Gibson said improving veteran access to care and services is a top priority, along with ending veteran homelessness.

"As the president has directed, we are moving immediately to get veterans off of wait lists and into clinics, and we're taking action to fix the systemic problems that allowed these unacceptable waits to occur," Gibson said.

The VA confirmed earlier today that it has now been in contact with 1,500 veterans in Phoenix, Ariz., of the 1,700 identified in a recent Inspector General report as having been kept on those secret waiting lists. The others not reached by phone have been reached out to by mail, the department said.

Gibson plans to travel Thursday to the Phoenix VA Medical Center, which is the epicenter of the scandal.