Former Alaska Governor Sarah Palin says she will not run for president, leaving little doubt that the eventual Republican nominee will come from the current field of contenders.
After months of leaving her fans guessing, Ms Palin said in a statement that she and her husband Todd "devote ourselves to God, family and country". She said her decision maintains that order.
Ms Palin sent the statement to supporters. She told conservative radio host Mark Levin that she would not consider a third party candidacy because it would assure President Barack Obama's re-election.
Senator John McCain plucked Ms Palin from relative obscurity in 2008 by naming her as his running mate. She electrified Republican activists for a while, delivering a well-received speech at the party's national convention. But Ms Palin later seemed overwhelmed by the national spotlight, faltering at times in televised interviews even when asked straightforward questions.
Ms Palin's announcement was much anticipated but not greatly surprising. Her popularity had plummeted in polls lately, even though she remained a darling to many hard-core conservatives. Some Republicans felt she waited and teased too long about a presidential candidacy. Some remained perplexed by her decision to quit her job as governor with more than a year left in her single term.
Ms Palin also angered some Americans with a defensive speech shortly after a Democratic congresswoman was gravely wounded in an Arizona shooting in January that killed six people.
Ms Palin's announcement came one day after New Jersey Governor Chris Christie said he would not run. Republican insiders say the field is set.
It includes former Massachusetts Governor Mitt Romney and Texas Governor Rick Perry, whom party insiders see as the strongest contenders. Libertarian-leaning Representative Ron Paul of Texas continues to draw a devoted following and former pizza company executive Herman Cain has gained in recent polls.
Voting in the Iowa caucus and New Hampshire primary will start in about three months.