WASHINGTON — Senate officials have postponed Wednesday’s scheduled confirmation hearing for Veterans Affairs Secretary nominee Ronny Jackson amid questions surrounding whether the White House may have missed serious concerns during his quick vetting process.

Jackson, a Navy rear admiral who currently serves as the White House physician, was a surprise pick for the VA post last month after President Donald Trump fired then-Secretary David Shulkin over Twitter amid ethics concerns and department infighting.

But Jackson’s lack of experience with VA drew immediate concerns from veterans groups and lawmakers, who noted the longtime naval doctor had no previous experience with any agency approaching the size (375,000-plus employees) and budget (nearly $200 billion) of the department.

As the confirmation hearing approached, lawmakers on the Senate Veterans’ Affairs Committee grew concerned with reports from former colleagues of Jackson and rumors of potential leadership issues during his military career, according to sources close to the debate.

Senators were scheduled to meet on Tuesday to decide whether to go ahead with the Wednesday confirmation, which was expected to include a host of detailed questions from Republicans and Democrats about the department’s inner workings and Jackson’s reform goals for the massive bureaucracy.

But the Washington Post reported on Monday night that committee leaders opted to postpone the event even before the Tuesday discussion. Committee officials did not return requests for comment.

Just a few hours earlier, White House officials released a letter signed by three former VA secretaries endorsing Jackson’s nomination, and White House spokeswoman Sarah Sanders told reporters that the administration had “a lot of confidence” in Jackson’s nomination.

Navy Rear Adm. Ronny Jackson, left, sits with Sen. Johnny Isakson, R-Ga. and chairman of the Senate Veteran's Affairs Committee, during a meeting on Capitol Hill on April 16, 2018. Jackson was slated to have a confirmation hearing before Isakson's committee later this week, but it was postponed on Monday night. (Alex Brandon/AP)
Navy Rear Adm. Ronny Jackson, left, sits with Sen. Johnny Isakson, R-Ga. and chairman of the Senate Veteran's Affairs Committee, during a meeting on Capitol Hill on April 16, 2018. Jackson was slated to have a confirmation hearing before Isakson's committee later this week, but it was postponed on Monday night. (Alex Brandon/AP)

The hearing delay now leaves the nomination in doubt and VA in further disarray. Shulkin’s firing was the second time in less than four years the department lost its leader in disgrace, and the Trump administration for the last year has had difficulty filling a host of high-profile VA jobs.

Trump appointed Defense Department Under Secretary for Personnel and Readiness Robert Wilkie to take over as acting secretary after Shulkin’s dismissal, with an eye toward him filling that role only for a few weeks or months. In doing so, they bypassed Deputy VA Secretary Thomas Bowman, a move that several veterans groups insist may have violated federal law.

Now, Wilkie’s tenure as the top VA official has a much longer timetable. If Jackson’s confirmation process resumes, it could mean only month’s delay. If his nomination is pulled, it could take months before a new nominee is named, vetted and confirmed.

Meanwhile, the department is facing a host of looming deadlines, including the exhaustion of funding next month for its controversial outside care program known as VA Choice. Wilkie has pushed for congressional action to fix that problem, but lawmakers have been wary of moving ahead too quickly with any measures while the VA leadership issue remains unresolved.