After more than a quarter-century on Capitol Hill, Jay Rockefeller (D) is finally the senior Senator from West Virginia and the leader of his state’s Congressional delegation. But for the 73-year-old chairman of the Commerce Committee, it’s just another day at the office.

Rockefeller, a self-described workaholic who looks forward to weekends so that he can catch up on the work that he couldn’t accomplish during the week, has operated at the center of American politics and national policy for a generation. Throughout he has remained a fierce advocate for West Virginia, using his seniority on several key committees to push legislation beneficial to the state that he adopted nearly 50 years ago.

Rockefeller dismisses talk that the death of Sen. Robert Byrd (D) — considered a patriarch of the Senate, let alone West Virginia — has in any way elevated his stature at home or changed his role in Washington, D.C. And although Rockefeller’s constituents and West Virginia’s forthcoming House freshman and junior Senator are sure to lean on him more than they might have otherwise in the wake of Byrd’s death, it is hard to argue the point.

As a former state legislator first elected in 1966, West Virginia secretary of state and two-term governor, Rockefeller’s Senate colleagues had long viewed him as among the most knowledgeable, experienced and “senior” junior Senators. During a recent interview in his office in the Hart Senate Office Building, Rockefeller warmly embraced that image when asked about the characterization — and then quickly brushed it off as irrelevant.

“Those things don’t matter — the junior or senior Senator. They never have; it’s just the way people can have fun with you,” Rockefeller said. “I love what I do, and it’s all very — it’s relatively simple for me because all I want to do is help the people of West Virginia.”

“And, you know, Byrd was that way,” Rockefeller continued. “He’d get into national issues, and I get into national issues. You can’t be on the Intelligence Committee and claim that you’re directly relating to West Virginia — except that you can. For example, Huntington, W.Va., is the seventh-largest port in the United States of America, which will come as a shock to you and to most West Virginians. I love what I do, and the reason I love what I do is I love the people for whom I do it.”

[IMGCAP(1)]Since Byrd’s death on June 28, Rockefeller has assumed responsibility for his appropriations priorities, calling it a “world of its own.” He said the task has necessitated several phone calls to Appropriations subcommittee chairmen to push for West Virginia’s priorities. “Byrd was very good at that,” Rockefeller said.

Gov. Joe Manchin (D) appointed Byrd’s successor Friday. Democrat Carte Goodwin, 36, Manchin’s former general counsel, is expected to serve until November, when the winner of a special election to finish Byrd’s term will take office. Manchin, 62, is expected to run and would be heavily favored. Rockefeller said he wants Manchin to run and is pleased that the special election will occur this November, rather than in 2012 as first envisioned.

Rockefeller, on hand in Charleston for Friday’s announcement, pushed Manchin to make the appointment quickly, noting that the vacancy almost imperiled the passage of financial regulatory reform and has made it harder for Democrats to muster the 60 votes needed to overcome a Republican filibuster of an unemployment benefits extension. Rockefeller said his priority moving forward would be to take the appointee “under my wing.”

“I’ll work with him. We’ve got to help him settle in,” Rockefeller said, prior to Goodwin’s appointment. “He’ll be the last in line for everything, and I want him to be effective, and he knows … that he’s only going to be there for four months.”

Rockefeller is the scion of America’s first oil magnate, and an heir to the vast family fortune spawned by his great grandfather and subsequently managed by his grandfather and grand uncles. The Senator was born in New York City and raised in all of the trappings such wealth provides, but he decided early on that the family blueprint for a life in business and Manhattan society was unappealing.

He graduated from Harvard, spent a few years studying in Japan and, after stints with the Peace Corps and the State Department, was urged to go to West Virginia by his best friend, Charles Peters, a native who eventually founded the liberal political journal Washington Monthly. In 1964, Rockefeller went to the tiny town of Emmons, W.Va., as a volunteer for VISTA, the forerunner to AmeriCorps, and what was intended as a 12-month sojourn became permanent.

In 1968, by this time the West Virginia secretary of state, Rockefeller had a chance to go back to New York and jump directly to the Senate, but he declined, having, in his words, fallen in love with the Mountain State and its people. “I like to say I was reborn, in the secular sense, in West Virginia,” he said.

New York Gov. Nelson Rockefeller (R) tried to recruit his nephew to accept a Senate appointment to succeed the late Sen. Robert Kennedy, who had been assassinated in California while campaigning for the Democratic presidential nomination. Rockefeller said the governor, his political team and other family members pressed him for 10 days to accept the appointment, but that it never occurred to him to say accept.

“I wanted to be a United States Senator, but I hadn’t grown to it,” Rockefeller said. “That would be nepotism.”

Since entering the Senate in 1985, Rockefeller has served as chairman of Veterans’ Affairs, Intelligence and Commerce committees. He played a prominent role in investigating intelligence failures in Iraq in the runup to the war and was key player this Congress in the health care reform debate — Rockefeller is chairman of the Finance Subcommittee on Health Care.

Rockefeller succeeded in slipping a regulation into the new financial regulatory reform law that forces publicly traded coal-mining companies to publicize their safety records. He failed to get the public insurance option into the health care reform law, but a number of his policy priorities survived the final bill.

Rockefeller can be irascible and aggressive when it suits his interests, but he has a warm, paternal quality that has fostered the trust and close relationships necessary for successful legislating in the Senate.

Majority Whip Dick Durbin (D-Ill.), a close ally, described Rockefeller as a “determined and tenacious fighter” who puts the interests of his state first. Appropriations Chairman Daniel Inouye (D-Hawaii) was similarly complimentary.

Sen. Debbie Stabenow (D-Mich.) referred to him as the “conscience” of the Finance Committee on health care reform.

“I think most Members view Sen. Rockefeller as a senior Senator,” Budget Chairman Kent Conrad (D-N.D.) said. “Sen. Rockefeller has a very distinguished record here over many years. He has positions of enormous responsibility and influence. … I think most colleagues treat him, view him, as a senior Senator and have for a long time.”