Sen. Edward Kennedy (D-Mass.) might be a legend, but even he can’t live forever.

And as a direct result, it’s unlikely that the eight-term liberal lionheart could hold his Senate seat forever, either.

Which is why if Kennedy, who is recovering in a Boston hospital after suffering a seizure Saturday morning, should announce his retirement any time before his 2012 re-election, civil war could erupt among Democrats in a rare statewide special election.

Kennedy, 76, was rushed to Cape Cod Hospital and later airlifted to Massachusetts General Hospital on Saturday after suffering a seizure in his Hyannis Port home. As of press time Monday, his aide said the cause of the seizure was still unknown but added that Kennedy is undergoing further evaluation and is resting comfortably with his family at the Boston medical center.

In 2004, Massachusetts lawmakers changed state law to force a special election — instead of the usual gubernatorial appointment — to fill a Senate vacancy. And for many Democrats — and even for the rare species of Republicans in the state — that could mean a free-for-all to replace the political icon.

A special election for a Senate seat is uncommon in state election laws, but the Massachusetts Legislature voted to change the law in 2004 when Sen. John Kerry (Mass.) was the Democratic presidential nominee and Republican Mitt Romney was governor. Under the old law if Kerry had won the presidency in 2004, Romney would have appointed his successor — likely a fellow Republican.

An overwhelmingly Democratic state Legislature voted to change the law to have a special election in the Bay State, which has not sent a Republican to Congress in more than a decade. Although Romney vetoed the bill, his pen was worthless against the Legislature, comprised of more than 90 percent Democrats.

Many of the Democrats in the Bay State Congressional delegation have been holding office for more than a decade — and chomping at the bit for the unlikely event that one of the two Senate seats might become open. Half of the Members of the delegation have at least seven figures in their campaign coffers, despite not having competitive re-election challenges in the past few cycles.

Rep. Ed Markey, in his 17th term, had the most cash on hand in the Democratic delegation as of the end of March: $2.4 million. He was followed by Rep. Richard Neal with $1.7 million, Rep. Bill Delahunt with $1.6 million, and Reps. John Tierney and Stephen Lynch with $1.2 million each. And in the less-than-a-millionaire club, Financial Services Chairman Barney Frank clocked in at $804,000 at the end of March, followed by Rep. Mike Capuano at $786,600.

As of March 31, Rep. Jim McGovern had $456,000 in cash on hand, Rep. John Olver had $322,000 on hand, and Rep. Niki Tsongas, the wife of the late Sen. Paul Tsongas (D) who won her seat in a special election in 2007, had $179,000 in the bank.

But the potential Senate candidates with the greatest cash advantage are no longer even serving in Congress: Recently retired Rep. Marty Meehan, who left his seat in mid-2007 to take the top post at University of Massachusetts at Lowell, has more than any of the state’s House Members with $4.8 million in his campaign bank account. Also out of office, former Rep. Joe Kennedy (D), the Senator’s nephew, had $2 million in his bank account as of March 31.

One Republican operative was willing to speculate who in the delegations past and present might make a go for the seat.

“If [Senator Kennedy] were to not run in 2012, it would be a free-for-all,” said the GOP operative. “Markey would almost certainly run. Barney Frank would almost certainly run. I wouldn’t be surprised if Joe Kennedy got in, he’s got $2 million cash on hand. And Marty Meehan has $4 million cash on hand.”

The Republican also speculated that McGovern could be interested in running some day, though Tierney, Tsongas, Olver and Lynch are unlikely to run because they have no base outside of their districts.

And though Massachusetts voters have not elected a Republican to Congress in for more than a decade, Harvard Pilgrim CEO Charlie Baker (R) has been rumored to be interested in a statewide bid, along with U.S. Attorney Michael Sullivan, former Lt. Gov. Kerry Healey (R) and former White House Chief of Staff Andy Card.

Erin P. Billings contributed to this report.