Another chapter in the long Palin-Murkowski rivalry opened today as Sarah Palin endorsed a Republican challenger to the Senate seat held by Lisa Murkowski.  Palin insists in her Facebook post that her support for Joe Miller rests on his pursuit of traditional conservatism, not personal grudges, and discusses a number of policy differences Palin has with Murkowski.  However, it’s impossible to ignore the political animosity between the two families that may have also contributed to this decision:

I’m proud to join so many other long-time Alaskans in supporting Joe Miller in the upcoming Alaska Republican Primary. Joe is a true Commonsense Constitutional Conservative, and we’re thankful he and his family are willing to offer us a choice in Alaskan leadership.

I share Joe’s belief that we are at a critical time in our nation’s history and the status quo will no longer do. Unfortunately, Lisa Murkowski and much of the political establishment have recently evolved into being a bigger part of the big government problem in Washington, and they’ve strayed from the principles upon which they had espoused. They ushered in the largest increase in federal domestic spending since Lyndon Johnson’s Great Society; it’s an increase in government that political machines may embrace, but “we the people” reject because we know it’s unsustainable and immorally burdensome to future generations.

Over a year ago, upon kicking off our Political Action Committee to assist candidates and promote competition in the nation’s electoral system, with no one willing to challenge the political machine at the time, and amid rumors that I would challenge Lisa Murkowski for the U.S. Senate, SarahPAC contributed to Lisa’s campaign. As she and I discussed, this was an attempt to reassure the Senator that I, as Alaska’s governor, had no intention of jumping into the race. Though the media has tried to portray some sort of feud or bad blood between Lisa and myself, such is not the case. I’ve always wished her well, but it is my firm belief that we need a bold reformer who is not afraid to stand up to special interests and take on the tough challenges of our time. Joe Miller has stepped forward. I am thankful for his willingness to serve. He has fought alongside me and others to help clean up the Republican Party here in Alaska by bringing in new leadership, new ideas, and commitment to putting government back on the side of the people, not any political machine.

Joe is a man of true integrity. He will never be bought off; he knows what a solemn trust it is to be given the responsibility of spending other people’s money prudently and wisely.

Palin became Governor and a national figure by running against the corruption in the Republican administration of Murkowski’s father Frank.  Already finished with her term as mayor of Wasilla at the time, Palin launched a clean-government campaign that pitted her against the elder Murkowski and the state GOP establishment.  Murkowski came in last in a three-way primary with only 19% of the vote, and to this day Palin frames her political career as that of a crusading reformer against establishment corruption and status-quo thinking.  That essentially puts the elder Murkowski in the eternal role of corruptocrat in the Palin narrative, which has to rankle his daughter.

None of that was lost on the younger Murkowski, either.  Last year, after Palin resigned as Governor, Lisa Murkowski took an opportunity to get even and publicly berated Palin for abandoning the state.  That certainly kept the rift open, and as Palin mentions in the above passage, it was public enough to fuel speculation that Palin herself would look for a second Murkowski scalp this year.  And Palin may well get it, but not as a candidate herself.

In her message, Palin focuses on policy differences, such as immigration reform, where she paints Murkowski as pro-amnesty.  The repeal of ObamaCare will be a big issue as well, and Palin accuses Murkowski of opposing it, as well as voting to use taxpayer money to fund abortions.  In a bit of a tightrope-walking, Palin also blasts Murkowski for supporting cap-and-trade legislation, but manages to avoid mentioning the support given to the same concept in the 2008 presidential campaign by her former running mate, John McCain, whom she has endorsed against J. D. Hayworth in Arizona.

Miller sounds like a solid Tea Party candidate, but Murkowski has been a fairly solid vote on issues like the EPA endangerment finding, for example.  It should be an interesting primary, and as Palin says, contested primaries are good for clarifying policy and performance.  We’ll see if Miller delivers the goods.

Update: Small correction to the original post; Palin had already completed her term as Mayor of Wasilla when she ran for Governor.  Thanks to Josh N for the assist.