Rear Adm. Ronny Jackson was tending to grievously injured military personnel in Iraq when he was summoned to Washington to interview for a job he barely knew existed. He didn't see a way to get there.

"I thought this was it — this is where the road stops," he told the Lubbock Avalanche-Journal this month.

Instead, Jackson managed to catch a ride on a transport plane that steered the Levelland, Texas, native toward some of the loftiest corridors of power.

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Jackson's journey has wound through the White House and across the globe, treating the blisters, stomach ailments and more of the past three presidents and their retinues. This coming week, Jackson is back on the interview circuit and heading toward the Senate for a hearing Wednesday on his nomination to be President Donald Trump's next secretary of the Department of Veterans Affairs.

"This will be the challenge of his life," said Robert Darling, a former White House physician who still dines occasionally with Jackson at the Army Navy Country Club.

Now it's time for Washington to examine Jackson, universally described as a reassuring presence in the most pressurized of atmospheres. But the 50-year-old apolitical Navy man has no experience leading a massive bureaucracy.

"He's got a great bedside manner you feel comfortable with," Sen. Sherrod Brown, D-Ohio, told The Associated Press. "But it doesn't mean he will be a good leader of the VA."

Some White House veterans privately say they're mystified at why Jackson is willing to move from practicing medicine to the insult-laden world of Trump-era politics at the head of scandal-plagued agency. Jackson did not respond to requests for comment from the AP.

But, in an interview with the Lubbock newspaper, Jackson defended his qualifications for the VA job. "I've been in leadership school for 23 years now. ... I've been confronted on a day-to-day basis with life and death decisions."

Mr. Trump abruptly named him to succeed David Shulkin, an Obama-era holdover fired under an ethical cloud and something of a staff rebellion. The president was delighted with Jackson's comprehensive and buoyant — some said fawning — briefing to reporters in January on Mr. Trump's "excellent" health and mental acuity.

Jackson has been an unknown on policy and it's not even clear he voted in the 2016 presidential election. The Hockley County Board of Elections in Texas shows he voted in 2015.

The only inkling of where he stands came when a few of the Democratic senators who met Jackson this past week reported that the nominee is promising not to privatize the VA. Shulkin's resistance to partial privatization, through expansion of a program letting veterans choose private care at public expense, compounded his lapses in travel spending and may have been the driving force in his dismissal. Where Jackson stands on enlarging the VA Choice program has yet to be teased out.

His path to this point is a winding one that did not start off pointing to medical school, emergency surgery or service to presidents.

In fact, in high school, Jackson went through "an ornery stage" that featured him cutting classes and ending up in the assistant principal's office at the business end of a wooden paddle.

"He got quite a few swats from me," recalls former Levelland High School assistant principal Kelly Baggett, a longtime family friend who now counts himself one of Jackson's biggest fans. "He took it like a man and shook my hand when it was over," Baggett said in a telephone interview. "Just a great kid, the kind you always want to visit with."

Jackson at first wanted to be a marine biologist, not a doctor. His direction changed after he took a job at the University of Texas Medical School as an autopsy assistant and found it interesting, according to an interview in the Lubbock newspaper. He graduated from Texas A&M University with a degree in marine biology in 1991.

He didn't plan on entering the Navy, either. But Jackson needed money for medical school, and he learned of a program in which he could be a Navy diver and a doctor, according to that published account.

Jackson got his medical degree in 1995 from the University of Texas and began active duty naval service that year at the Portsmouth Naval Medical Center in Virginia, his Navy biography says. Jackson graduated from the Navy's Undersea Medical Officer Program in Groton, Connecticut. He completed his residency back in Portsmouth and deployed as the emergency medicine physician in charge of resuscitative medicine for a forward deployed Surgical Shock Trauma Platoon in Taqaddum, Iraq.

The White House was another unplanned destination.

Jackson said he "got an email out of nowhere" saying he'd been nominated for a job at the White House. He then sped to Washington. Since President George W. Bush hired him in 2006, Jackson has cut a widely admired path among some of the nation's fiercest partisans — on intimate terms. Everyone who's recently worked in a president's inner circle, it seems, has a Ronny Jackson story.

Somewhere along the Pacific Rim in 2015, he treated the severely blistered toe of Obama's National Security Council spokesman, recalled the patient, Ned Price.

"Treatment consisted of bandages and tape, and it worked like a charm," said Price, who said he had been suffering from wearing new shoes for 20 hours straight. He like others described Jackson as a cool-headed and pleasant presence, "the guy you always want to be around."

"At no point was he down or stressed out," said Jen Psaki, who was Obama's communications director. She recalled Jackson reassuring her when she was pregnant that "if anything happens, we're good" whether on medically equipped Air Force One or in back in Washington. "I remember telling my husband that there's no safer place I could be than the White House."

It was Obama who elevated Jackson to director of the White House medical team and made him his physician.

Liz Allen, who served as Obama's deputy communications chief, said Jackson monitored her blood pressure for years and routinely would ask, even in passing, how she was doing.

"He is just so genuine," she said. "He treated people well. He always made you feel like you were the priority even when there were competing priorities."

Jackson is known for maintaining relationships. His connection to fellow Texan Bush, for example, survived the Bush presidency. In photos, the former president wears a reddish cap on a 2013 trip to Zambia, emblazoned with the name of Jackson's hometown, Levelland. Freddy Ford, a Bush family spokesman, said the hat had been given to Bush by Jackson's father, Waymon.