WASHINGTON – Shards from a Vietcong mine are still embedded in Chuck Hagel’s chest, 44 years after his infantry squad walked into a booby trap in the Vietnam jungle. Scar tissue marks the left side of his face from another mine explosion, barely a month after his first brush with death.

“I remember,” Hagel told an interviewer for the Library of Congress’s Veterans History Project in 2002, “thinking to myself, you know, if I ever get out of all of this, I am going to do everything I can to assure that war is the last resort that we, a nation, a people, calls upon to settle a dispute. The horror of it, the pain of it, the suffering of it.

“People just don’t understand it unless they’ve been through it.”

Today, Hagel heads President Obama’s short list of candidates to lead the Pentagon. If he is nominated by the White House and confirmed by the Senate, he would become the first defense secretary with a Purple Heart, the combat decoration for those wounded in battle, since Elliot Richardson, who held the job briefly during the Nixon administration.

Hagel served 24 months in the Army as an enlisted grunt before embarking on successful careers in business and politics that saw him earn millions and win election to the Senate, twice, as a Republican from Nebraska.

As a senator, he voted to authorize the war in Iraq but soon became the most vocal and cutting Republican critic of the George W. Bush administration, accusing it of bungling the occupation. In 2007, he warned that Bush’s plan to send 30,000 more troops to Iraq would be “the most dangerous foreign policy blunder in this country since Vietnam, if it’s carried out.”

His unbridled assessments left other Republicans wondering whose side he was on and thoroughly alienated the GOP’s neoconservative wing, which still hasn’t gotten over it. In recent days, some of them have intensified a campaign to shoot down his potential nomination even before Obama has made an announcement, ripping Hagel for what they see as his weak stance on Iran and his insufficient support of Israel.

“Stopping a war is a hell of a lot harder than starting it, and Chuck understands that,” said Democrat Bob Kerrey, another former Nebraska senator and Vietnam war hero.

“Sometimes it provokes cries from the right that he’s soft. But it’s just that he’s experienced it and it animates him.”

After toying with the idea of running for president in 2008, first as a Republican and then as an independent, Hagel decided instead to retire from the Senate and leave politics.

Disaffected Republicans back in Nebraska said he was scared of a primary challenge.

Some of Hagel’s opponents have implied that he is anti-Semitic. They cite a comment he made in an interview for a book published in 2008, when he said: “the Jewish lobby intimidates a lot of people up here.”

Abraham H. Foxman, national director of the Anti-Defamation League, said he does not believe Hagel is an anti-Semite – “absolutely not,” he said – but added that he does think the former senator’s position on Israel “borders on anti-Semitism.”

Sen. Richard Lugar, R-Ind., a foreign policy mentor to Hagel who is leaving the Senate after losing his re-election bid in a party primary, called the Nebraskan “an excellent candidate.”

But he stopped short of saying that Hagel would sail to confirmation.

“Most senators who served with Chuck would be favorable to his nomination,” Lugar said, before noting that the chamber has changed in makeup since Hagel left four years ago.

Might his nomination run into trouble? “I would hope not, but I have no way of knowing in advance,” Lugar replied.