The state's lone Republican member of Congress is Rep. Shelley Moore Capito of Charleston, a potential candidate. Her father, Arch Moore, was a popular Republican congressman and governor, who eventually landed in prison for fraud but remains well-liked.

“Capito has indicated that she wants to be in the Senate,” Maranto said. “In fact, she has talked about challenging Byrd in the past.”

But on C-SPAN recently, Capito said she would not run against Byrd because she did not want to run a negative campaign.

Maranto says the challenge for Capito is that she is a woman in a state with an electorate so old many voters do not think Byrd is all that old. West Virginia's median age of 40.7 is tied with Vermont as the "second-oldest" state in the nation. Only Maine, with a median age of 41.5, is older.

“They might find a woman senator who was raised in Washington and educated at Duke a little too newfangled for down-home West Virginia,” Maranto said. “That's just speculation, though. After all, West Virginia's other senator is a Rockefeller, and you can't get much more upscale than that.”

Besides Capito, two other Republicans would be considered strong potential candidates: Morgantown businessman John Raese, who ran for Senate in 1984 against Rockefeller, for governor against Arch Moore in 1988 and challenged Byrd for his Senate seat in 2006; or former West Virginia Secretary of State Betty Ireland.

Raese has personal wealth and name recognition to be taken seriously. Ireland probably would defer to Capito and instead seek her seat in Congress if she vacated it for a Senate run.

For West Virginians, no matter which party’s candidate eventually assumes Byrd's seat, the loss of the powerful Democrat would be felt from the state's Northern and Eastern Panhandles to the mountainous southern coal mines.

“Byrd’s legacy is one of enormous state and national power,” Sabato said. “He could not be dislodged in West Virginia under any circumstances because he brought tens of billions (of dollars) to the impoverished state.”

In West Virginia, as legend goes, Byrd is one of the state’s main industries. The state is full of places and roads built with federal money he brought home and, not coincidentally, often named for him.

In the Senate, Byrd rose to the peak of power as majority leader for a number of years and then became Appropriations Committee chairman.

“He helped his state's economy immeasurably,” Maranto said. “When I was in government in the Clinton years, every bureaucrat lived in fear that Byrd would move their office to Morgantown” from Washington.

A master of Senate procedure and great at giving history lessons on the Senate floor, Byrd at one time was an accomplished fiddler who made some pretty good bluegrass recordings, Maranto said.

"But he was also arrogant, vain and probably stayed around a few years too long,” he said.