The three Palin-backed candidates who have lost this season are Tim Burns in Pennsylvania's special election and GOP House candidates Vaughn Ward in Idaho and Cecile Bledsoe in Arkansas.

The nine who have won: Senate candidates Carly Fiorina in California, Rand PaulRand PaulPaul: Pence should oversee Senate ObamaCare repeal votes Healthcare fight pits Trump against Club for Growth GOP rep: Trump could be 'one-term president' if healthcare bill passes MORE in Kentucky and Rob PortmanRob PortmanOvernight Finance: Senators spar over Wall Street at SEC pick's hearing | New CBO score for ObamaCare bill | Agency signs off on Trump DC hotel lease GOP senators offer bill to require spending cuts with debt-limit hikes Vulnerable Senate Dem: Border tax concerning for agriculture MORE in Ohio; gubernatorial candidates Terry Branstad in Iowa, Nikki Haley in South Carolina, Susana Martinez in New Mexico and Rick Perry in Texas; and congressional candidates Tim ScottTim ScottA better economic policy Republicans rebuke King for racial remarks Conway on criticism: 'I'm not there to read about myself' MORE in South Carolina and Adam Kinzinger in Illinois. 

Palin, a potential Republican presidential candidate in 2012, has made a bunch of endorsements in other GOP primaries to come in the next several weeks. She is backing Clint Didier over Dino Rossi in the Senate primary in Washington state, congressional candidate Allen West in Florida and attorney Joe Miller in Alaska's Republican Senate primary, among others.

Other prominent Republicans, who are also potential 2012 candidates, scored wins Tuesday. Like Palin, former Massachusetts Gov. Mitt Romney backed Haley in South Carolina. And in the state's 1st district congressional runoff, former Arkansas Gov. Mike Huckabee was backing Scott.

Palin's endorsements this primary season have perplexed some observers. For the most part, she has endorsed conservative underdogs like Didier in Washington State and Bledsoe in Arkansas. But in other races she has gone with the establishment Republican — California's Senate primary and Iowa's gubernatorial primary are two examples.

Her backing of Branstad, where she passed over a more conservative, Tea Party-backed candidate, angered some of Palin's supporters.

In the Iowa race, it was Huckabee who backed the more conservative challenger, Bob Vander Plaats. Huckabee also broke with Palin and Romney in South Carolina in endorsing Lt. Gov. Andre Bauer in the primary for governor. Bauer came in fourth and Huckabee remained neutral in the runoff.

Unlike Palin, Romney has opted to avoid the political cycle's most contested Republican primaries. While Palin backed Ward in Idaho's 1st district primary in May, Romney stayed out of the race until after the primary. The day after, Romney made several endorsements in the state, including the candidate who defeated Ward, state Rep. Raul Labrador.

In all, Romney has made 13 primary endorsements so far this year and has only lost one. Romney backed Sen. Bob Bennett (R-Utah), who lost his spot on the ballot at the party's state convention last month.

— This post was updated at 11:20 p.m. with corrected information about the number of Palin's endorsements.