Former Alaska Gov. Sarah Palin (R) endorsed a Republican primary challenger to incumbent Sen. Lisa MurkowskiLisa Ann MurkowskiCongress should reject H.R. 1619's dangerous anywhere, any place casino precedent Democratic frustration growing over stagnating voting rights bills Graham emerges as go-to ally for Biden's judicial picks MORE (R-Alaska) on Wednesday.
Palin said she is backing attorney Joe Miller in his GOP primary effort to unseat Murkowski, a member of the Senate Republican leadership.
"I’m proud to join so many other long-time Alaskans in supporting Joe Miller in the upcoming Alaska Republican Primary," the 2008 GOP vice presidential candidate wrote in a Facebook post.
"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," Palin later added.
Palin's endorsement is arguably the most high-profile challenge she's made to establishment Republicans in Washington, where Murkowski serves as vice chairwoman of the Senate Republican Conference.
Palin and the Murkowski family, an Alaska political dynasty, have suffered from legendarily frosty relations. Palin challenged Murkowski's father, incumbent Gov. Frank Murkowski (R), in a 2006 Republican primary that led to Palin eventually winning the general election.
Since then, Murkowski has openly warned Palin against backing a GOP challenger to her reelection and blasted the governor when she resigned from office last year.
"I am deeply disappointed that the governor has decided to abandon the state and her constituents before her term has concluded," Murkowski said last year.
While Palin had stayed on the sidelines until now in the race, her husband, Todd Palin, had openly been backing Miller's candidacy.
The primary is August 24.