As Massachusetts Democrats in the state Legislature threaten to tinker with how U.S. Senate vacancies in the Bay State are filled, a mirror-image of the debate has been raging in Juneau, Alaska.

Two years ago, Democrats charged that Republican lawmakers in the Last Frontier cynically changed the succession law to deprive then-Gov. Tony Knowles (D) the ability to appoint a Senator in the event that then-Sen. Frank Murkowski (R) won the governorship, thereby having to leave the Senate before his term expired.

The Republican-controlled Legislature moved ahead with the change, Murkowski prevailed at the polls in 2002 and Knowles was denied the appointment.

Instead, newly sworn-in Gov. Murkowski was given that prerogative and promptly named his daughter, Lisa, a state Representative, to the Senate.

The law was changed to include a “waiting period” in which an interim Senator could not immediately be named. The window was just wide enough to shoo Knowles out the door and see Murkowski ushered in before a decision could be made.

Fast-forward to 2004 when Democrats in Boston are salivating at the prospect of Sen. John Kerry (D-Mass.) winning the presidency, thereby leaving a Senate seat open in the Bay state for the first time in 20 years.

Under current law, Massachusetts Gov. Mitt Romney (R) would name Kerry’s successor until a special election could be held in 2006.

Democrats do not relish that idea and instead want voters to fill the vacancy through a special election to be held within 60 to 180 days of Kerry’s presumed elevation to the White House.

Now the GOP is crying foul, saying it’s a sinister ploy to deny a Republican chief executive his gubernatorial right to appoint an interim Senator.

Sound familiar?

The situation in Alaska, which has had two more years to fester, is even more complicated.

Now a GOP lawmaker — who just happens to have been a good friend of Lisa Murkowski’s when she served in Juneau — wants to pass a law giving voters the right to fill Senate vacancies.

State Rep. Lesil McGuire (R) maintains that she has only the purest of motives — just as state Rep. William Straus (D), the author of the Massachusetts’ plan, insists.

Both say voters, and not governors, should get to play kingmaker.

That all sounds well and good but most Alaskan Republican lawmakers, including McGuire, voted against similar measures in Juneau before, Democrats say.

So why the change of heart now?

Democrats charge that it’s to head off a near-identical initiative from appearing on the November ballot, thereby saving Lisa Murkowski from embarrassment.

If the Alaska Legislature acts, the ballot measure to put the issue of who should fill Senate vacancies before the voters this year dies.

Three Democratic state legislators — Reps. Eric Croft, Harry Crawford and David Guttenberg — formed a group called Trust the People and rounded up the signatures.

Republicans said the trio did so to embarrass Murkowski by forcing her to appear on the November ballot alongside an initiative that calls into question the manner in which she came to the Senate.

Furthermore, the Alaska attorney general is challenging the legality of the measure.

McGuire says her bill, which passed the state House last week, removes the legal question and gives voters what they want — the right to fill such vacancies.

Some Democrats say they smell a rat.

In the past, GOP legislators have approved bills sufficiently similar to ballot initiatives, thereby throwing the measures off the ballot, then gone back and reversed themselves, said state House Minority Leader Ethan Berkowitz (D).

At least one Democratic ring-leader decided that Republicans were playing straight enough and voted for the McGuire bill.

Croft, one the Trust the People founders, said leaving the issue to the courts was too risky and cast his vote with McGuire.

The matter now heads to the Alaska Senate.

Even if the Murkowskis are able to sidestep the issue this year, there is also talk that Senate succession could become a topic of discussion a few years down the line. With Sen. Ted Stevens (R-Alaska) now 80 years old, there is persistent speculation that his son, state Sen. Ben Stevens (R), would seek to run for his seat when his term ends in 2008 — or seek appointment to the post if his father leaves Congress sooner.

Back on Beacon Hill, Democrats have yet to proceed with their plan but Romney and at least one prominent newspaper have already blasted them for even thinking about it.

“You really don’t want to create a monopoly that has so much power that it will say ‘we’re going to change laws in a blatantly partisan way’ at a time when people are looking to have fairness and equality on Beacon Hill,” Romney told the Boston Herald.