Mr. Griffin’s report brought immediate political consequences. For the first time since the controversy erupted last month, several Senate Democrats, including Mark Udall of Colorado and John Walsh of Montana, demanded that the secretary of veterans affairs, Eric Shinseki, step down, joining Republican lawmakers who have been making that demand for weeks.

Senator John McCain, Republican of Arizona, a former naval aviator who was a prisoner of war during the Vietnam War and is now an influential voice on veterans issues, also called on Wednesday for Mr. Shinseki to resign. Along with several other leading Republican lawmakers who had been withholding judgment, Mr. McCain asked the F.B.I. to investigate the Phoenix hospital. Mr. Griffin previously said that he was working with the Justice Department to examine whether criminal violations had occurred there.

Mr. Shinseki, in a statement, called the findings “reprehensible to me” and ordered the department to “immediately triage each of the 1,700 veterans” and give them timely care. The department suspended two senior officials at the Phoenix medical center shortly after the allegations of falsified waiting lists became public this month.

Jay Carney, the White House press secretary, said President Obama found the report “extremely troubling,” but he did not indicate whether Mr. Shinseki had lost the confidence of the White House.

Mr. Griffin’s interim report — the final version is expected by August — did not address the most explosive allegations made about the Phoenix facility: that as many as 40 veterans who were never put on the official list for doctors’ appointments might have died while awaiting care. He said determinations could be made only after examining autopsy reports and other documents that were still being reviewed. He had previously said that after reviewing 17 of those cases, he had found no indication that any of those deaths were tied to delays.