Sarah Palin announced today that she will not run for president.

ABC News’ Sheila Marikar and Shushannah Walshe report:

After months of “will she or won’t she” speculation, Sarah Palin hammered the nail into the coffin of her 2012 presidential aspirations: She’s not running.

In a statement obtained by ABC News and first reported by Mark Levin’s syndicated radio show, Palin said that she made her decision “after much prayer and serious consideration.”

“My decision is based upon a review of what common sense Conservatives and Independents have accomplished, especially over the last year,” she said. “I believe that at this time I can be more effective in a decisive role to help elect other true public servants to office — from the nation’s governors to Congressional seats and the Presidency.”

Read the full text of Sarah Palin’s statement.

The former Alaska governor addressed her fervent supporters, many of whom, like those running grassroots organizations dedicated to her all over the country, stepped away from their jobs and families to ramp up for her potential campaign.

“From the bottom of my heart I thank those who have supported me and defended my record throughout the years, and encouraged me to run for President,” she said. “Know that by working together we can bring this country back — and as I’ve always said, one doesn’t need a title to help do it. ”

She concluded, “In the coming weeks I will help coordinate strategies to assist in replacing the President, re-taking the Senate, and maintaining the House.”

Many observers speculated that Palin would not enter the race after she failed to announce in September — her one-time, self imposed deadline. She further indicated that the White House may not be in her sights last week, when she suggested that a presidential title might be too “shackle-y” on Greta Van Susteren’s Fox News show.

Still, her announcement comes as somewhat of a surprise. As recently as yesterday, Palin aides did not know whether she was running and were calling various states to find out filing deadlines for the primaries.

For some of Palin’s supporters, her decision not to run is heartbreaking.

Peter Singleton moved to Iowa almost a year ago to campaign for Palin, setting up a chapter of Organize4Palin in the first caucus state. He told ABCNews.com that he “expected her to run.”

“I’m disappointed, but disappointed for the country because he was the best choice for president at this time,” Singleton said. “I believed she would run, but I understood there was a chance that she didn’t. It was always her choice. And I have enormous respect for Gov. Palin as a leader and I respect her decision.”

ABC News’ Polson Kanneth contributed to this report.