Alaska Governor Sarah Palin will resign

Palin took no questions after a brief news conference in her hometown of Wasilla, Alaska, with Lieutenant Governor Sean Parnell and much of her state cabinet at her side. She gave no indication of her future plans.

"I'm not seeking re-election" in 2010, Palin said, adding she would transfer authority to Parnell on July 26.

Palin, McCain's surprise pick in the 2008 presidential race, rallied the party's conservative base. There has been speculation she would seek the Republican Party's presidential nomination in 2012.

"We are not retreating, we are advancing in a different direction," Palin said. "We know we can effect positive change outside government at this moment in time."

Palin, 45, said her decision came after much "prayer and consideration." She did not want to waste time on "political blood sport" and cited public criticism of her actions and her family since the 2008 campaign.

"You are naive if you don't see a full-court press right now on the national level picking apart a good point guard," Palin said, using a basketball analogy.

Palin complained during the unsuccessful 2008 campaign about having her comments "filtered" by the mainstream media.

Palin was cleared in November of wrongdoing in an abuse-of-power investigation into the firing of the state's public safety commissioner.

Last month, Palin signed a book deal to tell her own story, for an undisclosed sum, with News Corp's HarperCollins.

"I look forward to helping others -- to fight for our state and our country, and campaign for those who believe in smaller government, free enterprise, strong national security, support for our troops, and energy independence," she said.

(Additional reporting by Michelle Nichols, Andrea Shalal-Esa, Chris Wilson, Writing by Doina Chiacu, editing by Jackie Frank)