WASHINGTON — Almost a year after ordering a massive shake-up of the Veterans Affairs Department, President Obama gave one troubled outpost a once-over Friday to see whether his massive staff housecleaning led to improvements.

In a trip to the VA hospital in Phoenix, where a whistleblower exposed the existence of waits so long that dozens of veterans may have died awaiting treatment, Obama declared that his new VA leadership is “chipping away at those problems.”

“We’ve brought in a new team that has been tackling these issues to make sure that wait times for scheduling, access to providers, is greatly improved,” the president told reporters. “But what we know is there is still more work to do.

“Trust,” he said, “is one of those things that you lose real quick, and then it takes some time to build.”

Aides to the president say the Phoenix center has shown progress since the revelations last April, as has the rest of the agency’s division charged with providing health care to American veterans.

Promising accountability, new VA Secretary Bob McDonald fired or disciplined hundreds of employees and hired a net increase of more than 8,000 doctors, nurses and other health care workers, according to administration figures.

But change hasn’t come quickly or thoroughly enough for some veterans advocates who hope Obama will see the job as only half done during his review.

The conservative Concerned Veterans for America warned the president publicly against the perils of a “whitewashed tour” by hospital administrators who were part of the problem. A whistleblower who helped bring attention to the problems said she has seen signs of improvement but also expressed hope that Obama would get an unvarnished view, not just a meeting with senior executives.

“The person that he should be meeting with is the person that works the night shift on the psychiatric floor or who works the busiest shifts in the ER or the housekeeper that is struggling to clean all these really important places,” said Katherine Mitchell, a physician who testified before Congress last summer that she suffered retaliation routinely for reporting health and safety concerns at the troubled facility.

“If they want to find out what’s going on in the hospital, they need to speak with the people on the front lines,” Mitchell said in an interview before Obama’s tour.