WASILLA: Alaska Gov. Sarah Palin abruptly announced Friday she is resigning from office at the end of the month, a shocking move that rattled the Republican party but left open the possibility she would seek a run for the White House in 2012.

Palin, 45, and her staff kept her future plans shrouded in mystery, and it was unclear if the controversial hockey mom would quietly return to private life or begin laying the foundation for a presidential bid.

Palin's spokesman, David Murrow, said the governor didn't say anything to him about this being her "political finale." He said he interpreted Palin's comment about working outside government as reflecting her current job only.

"She's looking forward to serving the public outside the governor's chair," he said.

And Pam Pryor, a spokeswoman for Palin's political action committee SarahPAC, said the group continues to accept donations on its Web site, with an uptick in funds after Palin's announcement.

The announcement caught even current and former Palin advisers by surprise. Former members of the John McCain campaign team, now dispersed across the country, traded perplexed e-mails and phone calls.

But personal pressures have been mounting — scrutiny on her family, legal bills, ethics investigations and a running, public fued with McCain's camp that has flared up again.

In a hastily arranged news conference at her home in suburban Wasilla, Palin said she will formally step down July 26, and Lt. Gov. Sean Parnell will be inaugurated at the governor's picnic in Fairbanks. She said she had decided against running for re-election as Alaska's governor, and believed it was best to leave office even though she had two years left to her term.

"Many just accept that lame duck status, and they hit that road. They draw a paycheck. They kind of milk it. And I'm not going to put Alaskans through that," she said.

The 2008 vice presidential nominee was seen as a likely presidential contender in 2012 and had proved formidable among the party's base. But the last week brought a highly critical piece in Vanity Fair magazine, with unnamed campaign aides questioning if Palin was ever really prepared for the presidency. The backbiting continued with follow-up articles recounting the nasty infighting that plagued her failed bid. Her advisers sniped with other Republicans, underscoring the deeply divided GOP looking for its next standard bearer.

Meghan Stapleton, Palin's personal spokeswoman, shot down speculation that ranged wildly from Palin dropping out of politics altogether to eyeing runs against fellow Alaska Republicans U.S. Rep. Don Young and U.S. Sen. Lisa Murkowski. Palin's comment about serving outside government refers to the present, she said.

Stapleton, however, said it's too early to say whether Palin would seek the presidency. In the meantime, the governor will continue to work "toward affecting positive change as a citizen without a title right now," she said.

"Her vision is what's best for Alaska, which translates into what's best for America," Stapleton said.

Palin's resignation, timed on the eve of the July 4 holiday when many Americans had already begun a three-day weekend, seemed designed to avoid publicity. She alluded to how she could help change the country and help military members — code that she didn't think her time on the national stage was over.

One senior Palin adviser, who spoke to the family in recent days, described the governor and her husband as tired of the constant media scrutiny. Nevertheless, the adviser was shocked to hear Palin's announcement Friday.

A longtime confidant who spoke on condition of anonymity to discuss private conversations, the adviser counseled the Palins that leaving government was politically unwise, but the governor was resolute.

Though the announcement touched off a flurry of speculation among Democrats and Alaska political bloggers that Palin had been drawn into one of the many criminal investigations that have upended Alaska politics in recent years, the adviser reported seeing no evidence of such an investigation and said if one is under way, then Palin has kept it to herself and it would be yet another surprise to supporters.

Jerry McBeath, a veteran political science professor at the University of Alaska Fairbanks, called the pending resignation a "smart move," both for Palin and the state.

But political analyst Larry Sabato, in Charlottesville, Va., said Palin's announcement left many confused. "I think it eliminates her from serious consideration for the presidency in 2012."

Palin said her family weighed heavily in her decision.

"I polled the most important people in my life, my kids, where the count was unanimous," she said. "Well, in response to asking, 'Hey, you want me to make a positive difference and fight for all our children's future from outside the governor's office?' It was four yeses and one 'Hell, yeah!" And the 'Hell, yeah' sealed it."

Palin's decision not to seek re-election was a familiar one for a potential presidential candidate. Former Massachusetts Gov. Mitt Romney chose not to seek another term as he geared up for an unsuccessful 2008 presidential bid. Minnesota Gov. Tim Pawlenty has announced he won't seek another term, giving him plenty of free time ahead of a potential 2012 bid.

Palin emerged from relative obscurity nearly a year ago when she was tapped as then Republican presidential candidate John McCain's running mate.

She was a controversial figure from the start, with comedian Tina Fey famously imitating her elaborate updo and folksy "You betcha!" on "Saturday Night Live."

In the presidential race, Palin became the butt of talk-show jokes and Democratic criticism after news broke that the Republican Party had spent $150,000 or more on a designer wardrobe, accessories and hair and makeup services for her. The high-end spending spree contrasted with the down-to-earth image she sought to craft for herself and became an unwelcome issue for the McCain campaign.

She didn't leave the limelight once McCain lost the presidency. She recently led a public spat with "Late Show" host David Letterman over a joke he made about one of her daughters being "knocked up" by New York Yankees baseball player Alex Rodriguez during the governor's recent visit to New York. Palin's 18-year-old daughter, Bristol, is an unwed, teenage mother. Letterman later apologized for the joke.

Palin also complained that her 14-month-old son, Trig, who was diagnosed with Down's syndrome, had been "mocked and ridiculed by some mean-spirited adults recently." She didn't elaborate.

Fred Malek, a Republican strategist who has advised Palin over the past year, said Palin was "really unhappy with the way her life was going."

"She felt that the pressures of the job combined with her family obligations and the demands and desires to help other Republican candidates led her to decide not to run again. Once that decision was made, she realized, why not do it now and let the lieutenant governor take over and get a head start on his election," Malek said.

Palin's move also prompted speculation among bloggers and critics that the governor was facing a looming political crisis or embarrassment.

"There's got to be something below the surface that's about ready to come to the surface that quite potentially she just didn't want to deal with as governor," said Andrew Halcro, a Palin critic who lost the 2006 gubernatorial race to her.

There is, for example, a pending public records request from Linda Kellen Biegel, an Anchorage blogger who is seeking e-mails showing an effort by the Palin administration to smear her critics including those filing ethics complaints against the governor. Biegel, whose own ethics complaint was dismissed, also is seeking an investigation into the financial profits to the Palin family from racing sponsors of Palin's husband, Todd, in the 2,000-mile Iron Dog snowmobile race.

"There may be embarrassing things in there. I don't know," Biegel said. "I'm just as baffled as a lot of people."

Stapleton, Palin's spokeswoman, dismissed the rumors of damaging news on the horizon.

"No truth whatsoever. Period," she wrote in an e-mail to The Associated Press. "Just more nonsense from the same people who choose to waste state resources."

Palin was first elected in 2006 on a populist platform. But her popularity has waned as she became embroiled in partisan politics following her return from the presidential campaign. Her term would have ended in 2010.

Palin expressed frustration with her current role as governor.

"I cannot stand here as your governor and allow the millions of dollars and all that time go to waste just so I can hold the title of governor," Palin said, referring to the alleged impact of multiple ethics complaints against her, most of which have been dismissed.

Palin remaining as governor is not good for Alaska, given the "political bloodsport" by her critics, Stapleton said. Stepping down is a "fighter's move," Stapleton said, essentially Palin stepping around political barriers in her way and pursuing her vision.

Palin's announcement comes after several recent blows to the Republican party. Ensign, a member of the Christian ministry Promise Keepers, stepped down from the Senate Republican leadership last month after admitting he had an affair for much of last year with a woman on his campaign staff who was married to one of his Senate aides. Ensign later disclosed he had helped the woman's husband get two jobs during the affair.

A government watchdog group, Citizens for Responsibility and Ethics in Washington, wants the Senate ethics committee and the Federal Election Commission to investigate.

Just days after news of Ensign's affair broke, Sanford admitted an affair with a woman in Argentina. Some lawmakers are now calling for his resignation. Before the admission, Sanford had been missing from the state for five days visiting his lover. He had slipped his security detail, lied to his staff about where he was and failed to transfer power to the lieutenant governor in case of a state emergency.

The party's troubles seem to have left two prominent 2012 prospects, former House Speaker Newt Gingrich and 2008 presidential hopeful Mitt Romney, unscathed, however.

Palin has the potential to make far more money in the private sector than the $125,000 or so she has been making as governor.

Palin already had a deal with publisher HarperCollins to produce her memoirs, with publication planned for next spring. Terms of the deal have not been disclosed. Six-figure book deals are common for high-profile political figures.