Pete Hegseth, CEO of Concerned Veterans For America, waits for a meeting with Rep. Mick Mulvaney (R-S.C.) on May 15. (Ricky Carioti/The Washington Post)

Pete Hegseth leaned forward on the brown leather sofa in Rep. Mick Mulvaney’s office and began his rapid-fire pitch:

Captain in the Minnesota National Guard. Served in Baghdad and Kabul. Now running an organization of veterans and families.

Sixty seconds in, when meetings between veterans and members of Congress usually turn to the importance of protecting health and retirement benefits, of the GI Bill and disability benefits, Hegseth swerved in the other direction.

“I’m not here to ask you for anything,” he told the South Carolina Republican. “I’m here to be an advocate for fiscal responsibility in Washington.”

Mulvaney betrayed an incredulous expression.

“That would make you a rarity among people who come into this office,” he said.

Hegseth, a Republican whose résumé includes Princeton and Harvard as well as a stint as a guard at the Guantanamo Bay prison, runs a small and scrappy group called Concerned Veterans for America. It is far smaller than the American Legion, the Veterans of Foreign Wars or other well-known veterans service organizations. But it is unusual in its mission: Instead of advocating for more benefits, he wants to provide political cover to legislators who want to make what he calls “tough decisions about our military.”

“We’re here to help you when you stick your neck out,” he said.

Hegseth’s group is not offering specific policy prescriptions, but it is supporting cuts of some sort — and that puts it in a unique niche in the battle over military funding. Lawmakers and their aides have been increasingly willing to meet with him in recent months, intrigued to hear his views and to gauge whether he has the members to provide the promised support if they choose to embrace positions that run counter to the large veterans organizations.

Although his army still is modest — he has only 25 field organizers nationwide — his message is attracting attention among veterans. Some applaud him for taking on the established veterans lobby, which has become almost sacrosanct in Washington. Others see him as a traitor who is seeking to deprive active-duty personnel and veterans of well-deserved pay and benefits.

Hegseth, whose dark wavy hair has long outgrown military regulations, said neither characterization is accurate. He doesn’t want to gut benefits, and he’d rather work with other veterans groups, but he recognizes cuts to the military are inevitable and necessary. Instead of opposing all reductions, he wants veterans to lead the process, sharing their experience — “We all know where the waste is,” he said — to trim the budget in a way that doesn’t sap troop strength, training and critical equipment.

“In order to preserve the muscle, you have to be serious about cutting the fat,” he said over a barbecue lunch in the Longworth House Office Building cafeteria after his meeting with Mulvaney. “Do you want tuition assistance or the 101st Airborne?”

He quickly added that he wasn’t trying to advocate the elimination of tuition assistance for troops pursuing college degrees while serving. Although his organization has not come up with a list of proposed cuts, he said he would be in favor of transforming the current retirement system — which provides pensions for those who stay for 20 years or more, and nothing for those who leave earlier — with a program that more closely resembles a private-sector 401(k) plan.

“We don’t claim to have all of the solutions,” he said. “We want to create the space for smart people to do the right thing.”

In between his undergraduate studies at Princeton and the master’s he earned last month from Harvard’s Kennedy School of Government, Hegseth worked on Wall Street and deployed three times. And he played rough-and-tumble politics.

In 2008, he was the executive director of Vets for Freedom, which argued for a troop surge in Afghanistan and against a pullout of forces from Iraq. But by 2010, fighting big wars was no longer a winning issue. He recalibrated by allying himself with the tea party movement.

“Those were the issues of the day back then,” he said of the wars. “Today, it’s about getting our fiscal house in order.”

He has not won many friends in the Obama administration with his full-throated attacks on the president’s Iraq policy and his opposition to Chuck Hagel’s nomination to be defense secretary. Hegseth had been concerned that Hagel lacked the commitment and management skills to transform the Pentagon, but after hearing him speak about the need to address the growth of personnel costs, Hegseth said he is reserving judgment. “We could be strange bedfellows,” he said.

Although Hegseth wants to work with Democrats, his target audience is budget-conscious Republicans.

“Being a defense hawk and a budget hawk are not mutually exclusive,” he told Mulvaney.

The congressman nodded. The GOP, he said, too often “equates spending [on defense] with commitment.”

“There needs to be a more nuanced message,” Hegseth responded. “It’s possible to be strong and lean.”