President Barack Obama speaks at Newport News Shipbuilding on Tuesday as part of his public campaign to sway Congress to block automatic spending cuts that are scheduled to begin on March 1 in defense and domestic programs. (Steve Earley/Associated Press/The Virginian-Pilot)

At the bustling shipyards of Newport News, near where President Obama on Tuesday decried looming budget cuts, workers are building the USS John Warner, the only Virginia-class nuclear submarine to be named for a man rather than a place.

The 377-foot vessel serves both as a symbol of the military’s high regard for the longtime Republican senator and a sobering reminder that, with the sequester about to hit, the commonwealth may not carry the weight it once did in the halls of the Pentagon.

“No one has assumed John Warner’s spot. It just hasn’t happened,” said Rep. J. Randy Forbes (R-Va.). “That was a huge gap for Virginia.”

A loss in clout could be painful for the home of the Pentagon, the world’s largest naval base and scores of defense contractors. The military is the state’s biggest employer and a key reason why its economy has stayed afloat while many others have floundered in recent years.

For more than three decades, when Virginia spoke up, the military listened.

Warner, a veteran of World War II and Korea and former secretary of the Navy, held instant credibility on military matters when he was elected to the Senate in 1978. He became chairman of the Armed Services Committee in 1999 and held the top Republican slot until he retired a decade later.

Warner worked well with presidents and lawmakers from both parties and helped keep military money flowing to the state, including millions for aircraft carriers and subs built at Newport News.

James Webb (D) became the state’s junior senator in 2006. Also a former Navy secretary and a decorated Vietnam veteran, Webb spent one term in the chamber and was more introverted than Warner. Still, he made his presence felt.

In 2010, Virginia leaders were frustrated that the Pentagon planned to close the Norfolk-based Joint Forces Command. For months, they tried to get a meeting with Robert M. Gates, who was then defense secretary. Finally, Webb threatened to hold up every Defense Department nomination pending in the Senate. Virginia got its meeting.

“I think you can’t underestimate stature,” Rep. Gerald E. Connolly (D-Va.) later said of the episode.

Joint Forces Command eventually closed, but many of its jobs were preserved. Virginia lost some battles on Warner’s watch, too, and it’s unlikely a single lawmaker could succeed in forestalling the sequester, which will hit the state particularly hard.

Roughly 90,000 civilian Defense Department employees in the state could be furloughed, the White House warns, while the Navy could cancel maintenance of 11 ships at Norfolk and a host of other projects could stall.

Virginia lawmakers “are certainly important figures, but I think the problem here is sequestration is kind of influence-proof,” said Anthony H. Cordesman, a former Pentagon official now at the Center for Strategic and International Studies.

Virginia still has its share of players on Capitol Hill. Sen. Timothy M. Kaine (D) has succeeded Webb on both the Armed Services and Foreign Relations committees.

In the House, three Virginia Republicans — Scott Rigell, Rob Wittman and Forbes — serve on the Armed Services Committee, with both Forbes and Wittman heading subcommittees. Rep. James P. Moran (D) sits on the appropriations panel that oversees defense spending, and Rep. Eric Cantor (R) is the House majority leader.

Several House members teamed up with Webb and Sen. Mark Warner (D) last year to stop a Navy plan to move an aircraft carrier from Norfolk to Florida, prevailing after a pitched battle with the Sunshine State’s congressional delegation.

Virginia still has the committee seats, but it doesn’t have a star. None of the House members has the national profile on security matters that John Warner and Webb did. Kaine and Mark Warner are both former governors, but neither has direct military experience (though Kaine’s son, Nat, is a second lieutenant in the Marine Corps).

Kaine, who recently hung a framed picture of Webb and John Warner on his office wall, said that “there has been the erosion of some of that relationship-based bridge building” at which Warner excelled.

Wittman agreed that Congress has changed but said “the clout is still there” for Virginia, particularly because the delegation meets monthly and works well across party lines on military issues.

On the bright side, Virginia has a new reason to be lavished with attention — it’s a swing state.

“Virginia now is really front and center in political importance nationally,” Kaine said, “and both both parties see it.”

Michael Laris contributed to this report.