Acting Veterans Affairs Secretary Sloan Gibson briefly addressed the problems involving wait times at VA hospitals Wednesday, calling them "unacceptable" and saying the agency is working quickly to clear the backlog.

Gibson's remarks came days after being named as a temporary successor to Eric Shinseki, who resigned as VA secretary on Friday.

Shinseki resigned days after an interim VA report confirmed allegations of long wait times and false record-keeping.

Gibson spoke at the White House, where he, first lady Michelle Obama and others announced a coalition with mayors to end veterans' homelessness.

"Ending veterans' homelessness is one of VA’s 3 agency priority goals. Under the circumstances, I would be remiss if I didn’t at least mention one other goal that we have, and that’s improving veteran access to VA care and service," Gibson said.

Acting Veterans Affairs Secretary Sloan Gibson speaks at the White House on Wednesday. (Gary Cameron/Reuters)

"As the president has directed, we are moving immediately to get veterans off of wait lists and in clinics, and we’re taking action to fix the systemic problems that allowed these unacceptable waits to occur. We demonstrated in the past our ability to tackle tough challenges. We automated the claims process and cleared half the backlog, and we’re on our way to eliminating veterans' homelessness."

Obama said that while the number of homeless veterans has dropped, it is still unacceptable.

"Even one homeless veteran is a shame. And the fact that we have 58,000 is a moral outrage. Tens of thousands of veterans who risked their lives for our country are sleeping in their cars or in a shelter or on a subway vent," Obama said. "We should be horrified."

Mayors around the country are partnering with the White House, as well as local and non-profit organizations to help end veterans' homelessness. It builds off the administration's Housing First initiative, which connects veterans with homes.

“When a veteran comes home kissing the ground, it is unacceptable that he should ever have to sleep on it," Obama said.