Washington (CNN) - Sarah Palin broke ranks with the conservative movement on Thursday and endorsed former Hewlett-Packard CEO Carly Fiorina in California's Republican Senate primary, prompting a flurry of criticism from many of her loyal supporters.
After Palin announced the endorsement on her Facebook page, a number of her followers questioned why she would side with Fiorina instead of the more conservative candidate in the race, Assemblyman Chuck DeVore.
DeVore has the backing of several leading voices in the conservative movement, including Sen. Jim DeMint, RedState.com editor Erick Erickson and the Tea Party Express.
Though a handful of readers agreed with Palin's decision, most were upset.
"This is very, very disappointing," Rick Sheridan, one of her supporters, posted on Palin's page. "Sarah, you've got to be more careful. This woman does not represent conservative values. And the choice is so clear. Serious damage to your base here."
"Wow, Sarah...I'm saddened and shocked by your decision to endorse Carly Fiorina," commented another backer, Jennifer Goode. "Had you done your research, you would have found that Chuck DeVore is the ONLY true conservative in the California Senate race."
Also in the GOP race is former Rep. Tom Campbell, who has maintained a steady lead over his opponents in recent polls. The Republican nominee will take on Sen. Barbara Boxer in the general election.
The former Alaska governor explained her decision to wade into the primary by taking a shot at Campbell - but she made no mention of DeVore.
"I'm a huge proponent of contested primaries, so I'm glad to see the contest in California's GOP, but I support Carly as she fights through a tough primary against a liberal member of the GOP who seems to bear almost no difference to Boxer, one of the most leftwing members of the Senate," Palin wrote.
DeVore spokesman Joshua Trevino said the swift reaction from conservatives online speaks for itself.
"I think the best I can do is point you toward the responses from the conservative base on Palin's Facebook page, and on Twitter: there's a lot of them respectfully but firmly telling the former Governor that she's been misled here. And they're right," he said in an email.
Palin also irked some conservatives earlier this year when she endorsed Sen. John McCain, who elevated Palin to the national stage, in his Senate primary battle against former Rep. J.D. Hayworth.
Her loyalty to McCain may have been a factor in the California race, as well. Fiorina was one of McCain's economic advisers during the presidential campaign, and last year she told reporters: "I share Sarah Palin's values."
UPDATE: Fiorina's team disputed the notion that Palin's endorsement is inconsistent with the the Tea Party movement. Spokeswoman Julie Soderlund pointed to a recent Field Poll that found Tea Party supporters prefer Fiorina over Campbell and DeVore.
"Whether or not Chuck DeVore wants to admit it, Carly is a conservative and political outsider," Soderlund said.
Campbell's campaign, meanwhile, said the endorsement is nothing more than an "IOU from the 2008 election cycle."
"California voters are not buying that a failed CEO can be an effective U.S. Senator," a Campbell spokesman said. "Voters are looking for a Republican with a balance of experience, a real record fighting wasteful federal spending and the ability to defeat Barbara Boxer - and poll after poll says that Republican is Tom Campbell."
UPDATE 2: Palin updated her Facebook post after the uproar and listed Fiorina's conservative credentials, including her opposition to abortion rights, her support for gun rights and opposition to "Obamacare."
"And most importantly, Carly is the only conservative in the race who can beat Barbara Boxer," she wrote. "That’s no RINO. That’s a winner."