The death of Rep. John Murtha (D-Pa.) on Monday sent shock waves through the Democratic ranks, stunning Congressional allies who hoped he was on the mend after complications from a recent surgery and raising questions about a power vacuum left by his passing.

The loss was felt most powerfully in the close circle of friends and acolytes, most from lunch-pail districts across the Rust Belt, who regularly gathered around his semi-official perch in the southeast corner of the House chamber, known as “Murtha’s corner.”

“Our state has lost its giant,” Rep. Mike Doyle (D-Pa.) said.

And lawmakers from the Keystone State and beyond said they had lost an organizational pillar — a mentor on the ways of the House, a powerful source of support for hometown projects, an encyclopedia of information on defense issues, and a fearsome advocate for his party in what has become a bitter, partisan scramble for the high ground in the national security debate.

His death reverberated, too, at the top of the Democratic leadership ladder, where he was a key booster and longtime ally of Speaker Nancy Pelosi (Calif.). Like many of his closest friends scattered through the Democratic Caucus, Pelosi honored him as a “great patriot.”

“As a proud Marine, he was always Semper Fi!” she said in a statement.

Others in his orbit struggled to assess the loss Monday even as they started to grieve for a friend who they had been hoping would soon be rejoining them. Murtha was readmitted to the hospital last week for treatment for an infection that he developed after scheduled surgery to remove his gallbladder. After a dicey period, he appeared to be recovering.

Doyle said that when Murtha was well enough to accept visitors, “we were going to plan a little surprise trip down there with the guys who hang out in the Pennsylvania corner.”

Democratic lawmakers remembered Murtha, a Vietnam veteran, as both a careful student and peerless master of defense policy who formed stances based on his considerations of how they would affect the soldiers.

“He was not an icon,” Rep. Bill Pascrell (D-N.J.) said. “That would not suit Jack well. He was a Marine, a tough Marine. He had his feet on the ground.”

Shadowed in recent years by questions about his ties to defense industry lobbyists, Murtha remained unapologetic about what he described as dogged advocacy for his district. He leveraged his seat atop the Appropriations Subcommittee on Defense to bring military contractors there to revive an economy devastated by the collapse of the steel industry. “When guys would take issue with his earmarks …  it never bothered him a bit,” Doyle said. “He said, ‘Everything I have done, I have done on principle.'”

Pascrell recalled a conversation that he had with Murtha in the Pennsylvania Democrat’s office as he faced charges about his earmarking. “He said to me, ‘Do the best you can. There’s always going to be people who say this or that. And if you can’t stand the hot water, get the hell out of the business.'”

Rep. Marcy Kaptur (D-Ohio), a longtime colleague on the defense spending subcommittee, said Murtha’s intellect was often underestimated. “He had this Irish-American demeanor — a quick, brusque style, always with a twinkle in his eye,” she said. “A lot of people took that at its surface value and never really saw his encounters on defense issues. If you did, you would be awed. … And this was a man who could have been Speaker. He could remember votes from 10 years ago — the margin, how people voted.”

Doyle said it is impossible to replace the kind of influence that Murtha carried in the House. “Whoever takes Jack Murtha’s seat in Congress is going to wait an awful long time to fill one of those shoes, let alone two,” Doyle said.

Murtha’s death also closes the book on his controversial practice of providing earmarks for his district. Last month, the Office of Congressional Ethics closed its investigation into earmarks that he provided to clients of the now-defunct PMA Group lobbying firm and advised no further investigation by the Committee on Standards of Official Conduct, commonly known as the ethics panel. Standards has not publicly acknowledged that referral, nor is it likely to. Under House rules, the ethics committee is not required to publicly release any information when the OCE recommends a case be dismissed, nor is it required to release the related report.

The ethics committee has acknowledged its own investigation centered on PMA, but it has never identified which Members it is examining or what House rules those lawmakers may have violated in their interactions with PMA.

Even if the House ethics panel had targeted Murtha in its investigation, however, the committee’s inquiry into the Pennsylvanian would end with his death.

“As a general matter, the jurisdiction of the ethics committees, the House and the Senate, extends only to Members, officers and employees of the respective bodies,” said Rob Walker, an attorney with Wiley Rein who was previously a top aide to the Senate and House ethics committees.

“With respect to any inquiry that may be going on … the death of the Member should end that matter,” Walker said, emphasizing that he was speaking generally about Congressional investigations, not about Murtha specifically.

However, Walker added, “If there’s an inquiry that involves multiple Members, obviously the passing of one of them would not end an inquiry altogether.”

In addition, an ethics investigation of a Member who has died will not necessarily immediately exempt any of the lawmaker’s staff from an ongoing investigation.

Jennifer Yachnin contributed to this report.