WASHINGTON — Ronny L. Jackson, President Trump’s choice to lead the Department of Veterans Affairs, is facing mounting skepticism from Senate Republicans over whether he has the management experience to lead the nation’s second-largest bureaucracy.

The comments from several GOP senators, particularly those with influence on veterans’ issues, signal Jackson will have to work overtime to persuade not just Democrats but Trump’s own party that he is qualified to oversee the beleaguered agency. That challenge comes at a time when Senate Republicans are already juggling other controversial nominations that will consume much of the political oxygen on Capitol Hill.

Jackson has served three administrations under both parties as the White House physician, yet has little management experience on his résumé as he gears up to take over a sprawling agency of 360,000 workers and deal with the vexing challenges of providing health care and benefits to military veterans. Republicans say they know little to nothing about Jackson and are quickly studying up as they prepare for one-on-one meetings with the nominee.

‘‘Certainly, I do have concerns about his experience, as far as managing people,’’ said Republican Senator John Boozman of Arkansas, who sits on the Senate Committee on Veterans’ Affairs, which will vet Jackson’s nomination. ‘‘There is some concern about whether or not he’s been in a position to lead an organization like that.’’

Senator Jerry Moran, a Kansas Republican and another committee member, also expressed worries about Jackson.

‘‘The VA is a difficult place to manage, regardless of what your background experience is. I want to know more about how he believes that he’s capable of fulfilling those responsibilities and I have a wide array of questions in regard to his experience and background,’’ Moran said. ‘‘I need to be convinced that he can make a difference at a department in which the culture and the upper echelons of its leadership need to have somebody who can take charge.’’

At best, Jackson is getting a tepid reaction from Senate Republicans, many of whom had praised his ousted predecessor, David Shulkin, even if they occasionally clashed over policy. Democrats were also vocal supporters of Shulkin, the sole Cabinet holdover from the Obama administration who was the rare Trump-appointed official who sailed through the Senate with no objections.

A White House spokesman did not return a request for comment Tuesday on the Senate Republicans’ concerns surrounding Jackson’s qualifications. But the White House has defended Jackson’s credentials in the past, and the physician himself laid out his leadership background in an interview with a local newspaper in Texas published over the weekend.

‘‘I’ve been in leadership school for 23 years now. . . . And I’ve been able to rise to the level of an admiral, a flag officer in the Navy. I didn’t just stumble into that,’’ he told the Lubbock Avalanche-Journal.

He added: ‘‘I think I’ve got what it takes, and you know, I don’t buy into that argument at all.’’

Democrats are also questioning whether Jackson can handle oversight of the massive bureaucracy, which is second only to the Pentagon in size. But they’re also making it clear that Jackson’s nomination will be intertwined with the broader fight about whether veterans should have more access to private doctors at taxpayers’ expense.

Shulkin had worked with senators on a bipartisan compromise that would largely keep VA in control of whether veterans can obtain private health care, while removing some restrictions. But the White House has pushed for a more aggressive turn toward privatization, which has alarmed Democrats and some veterans’ groups who worry about outsourcing so much of veterans’ care outside of VA.

Senator Patty Murray, a Washington Democrat, said she wants to hear from Jackson that he is ‘‘unequivocally opposed to privatization.’’