PHOENIX - Amid persistent complaints about veterans' health care, President Obama acknowledged lingering weaknesses Friday in the federal government's response to the chronic delays and false waiting lists that triggered a national outcry last year over the Veterans Affairs health system.

Obama said that while VA Secretary Robert McDonald was "chipping away" at the problem, it was clear there was still more work to do. "It's important that veterans know that somebody's got their backs and that if there are problems that we're not being defensive about it, not hiding it," Obama said.

In his first trip to the Phoenix VA hospital whose practices sparked the scandal, Obama announced the creation of an advisory committee to recommend further steps the VA could take to improve veterans' access to health care.

Obama met with veterans, VA employees, and elected officials, including Arizona's senators, John McCain and Jeff Flake, both Republicans. He said lawmakers asked about the slow pace of implementing a law meant to increase health-care choices for veterans. Mental health and suicide prevention are also areas of concern, he said.

"Trust is something you can lose real quick," Obama said, promoting the need to restore trust and confidence in the VA system. But, he added, "every veteran I talked to today said that the actual care they received once in the system was outstanding."

Obama's visit came amid questions from lawmakers who say veterans are still not benefiting from changes in the law that were meant to improve their access to care.

McCain, chairman of the Senate Armed Services Committee, blasted the president's visit as a "photo op." He said the foot-dragging in implementing VA reforms showed the Obama administration had given up on reform before it even started.

"The American people - and veterans in particular - should be as unimpressed by the president's high-profile but empty gesture today as I am," said McCain, who held a news conference outside the VA.

As Obama flew to Phoenix, the White House defended the VA's actions to correct problems. "Long after it fades from the headlines, this is something a lot of people have been working on and that the president feels strongly about," White House spokesman Eric Schultz said.

Aiming to illustrate a more positive veteran's story, Obama also visited Sgt. 1st Class Cory Remsburg, who was wounded in Afghanistan and has met with Obama several times. Remsburg recently moved into a home purchased by a nonprofit that helps disabled Army Rangers, and the president brought along White House beer as a housewarming gift, the White House said.