Washington (CNN) - Republican Brian Murphy is heading into Tuesday's GOP gubernatorial primary in Maryland with a last minute robocall from conservative star Sarah Palin.
Just hours earlier, Sen. John McCain – Palin's former presidential running mate – had announced his support for Murphy's primary opponent, former Gov. Robert Ehrlich in an interview with the AP, saying Ehrlich is "a fine guy."
But the split is not surprising given the roster of candidates Palin has chosen to support this election cycle, as she has often broken with the Republican establishment. Her endorsement of Joe Miller in the Alaskan Senate GOP primary is widely credited with helping to propel the formerly little-known candidate to an upset victory over incumbent Sen. Lisa Murkowski.
In Delaware, Palin's support of Republican Christine O'Donnell – for whom she also recorded a robocall today – has helped the conservative candidate close ground against moderate Rep. Mike Castle in the state's GOP Senate primary race.
Murphy is similarly seeking to portray himself as a political outsider. In the robocall, Palin calls Murphy a "proven business leader. Not a career politician." Palin had previously endorsed Murphy in August, touting him as "common sense" conservative, but had mostly stayed silent on the race until now.
Nonetheless, Ehrlich is widely considered to be the favorite in the primary set for Tuesday. Though not an incumbent, Ehrlich previously served as Maryland's governor for one term before losing his reelection bid to Democrat Gov. Martin O'Malley in 2006.
The winner of Tuesday's GOP primary will face O'Malley, who is seeking a second term, setting up a potential rematch between the former opponents.
– CNN Politcal Producer Peter Hamby contributed to this report