WASHINGTON — Seeking to head off a growing furor over veterans’ health care, President Barack Obama declared Wednesday that allegations of misconduct at Veterans Affairs hospitals are “dishonorable” and will be not be tolerated by his administration.

“I will not stand for it — not as commander in chief but also not as an American,” Obama said following an Oval Office meeting with embattled VA Secretary Eric Shinseki.

The Obama administration is under mounting pressure from Capitol Hill to address troubling allegations of treatment delays and preventable deaths at VA hospitals. The VA Inspector General’s office said late Tuesday that 26 facilities are being investigated nationwide — up from 10 just last week — including a Phoenix hospital where 40 veterans allegedly died while waiting for treatment and staff there kept a secret list of patients waiting for appointments to hide delays in care.

Obama vowed to hold anyone found to have manipulated records accountable, but continued to stand by Shinseki, despite calls from some congressional lawmakers for the retired Army four-star general to resign.

“We are going to fix whatever is wrong and so long as I have the privilege of serving as commander in chief, I’m going to keep on fighting to deliver the care and the benefits and the opportunities that you and your families deserve, now and for decades to come,” Obama said.

The president spoke hours before the House was scheduled to vote on a bill that would grant the VA secretary more authority to fire or demote senior executives. The White House has said it shares the goals of the House measure — to ensure accountability at the VA — but has concerns about some of the details.

Obama’s statement marked his first public comments on the matter in more than two weeks. Last week, he dispatched his deputy chief of staff Rob Nabors to the VA to oversee a review of department policies and ordered him to report back to the White House next month.

Nabors, who also took part in the Oval Office meeting, was heading to Phoenix later Wednesday to meet with staff at the VA hospital at the center of the allegations, including interim director Steve Young and other hospital administrators.

The current director of the Phoenix VA Health Care System, Sharon Helman, has been placed on leave indefinitely while the VA’s inspector general investigates the claims raised by several former VA employees. Investigators probing the claims say they have so far not linked any patient deaths in Phoenix to delayed care.