Sarah Palin has officially closed the door on a 2012 White House run, telling supporters Wednesday that her family comes first, and that she feels she can better serve the conservative cause without chasing the "title" of president. With New Jersey Gov. Chris Christie also formally opting out of the race this week, Palin's announcement leaves the GOP slate of candidates pretty set in stone. After months, if not years, of hinting she might run for president, why did Alaska's former governor ultimately decide to sit out this year? Here, five theories:

1. Palin knew she couldn't win
President Obama is beating Palin in a hypothetical match-up in "oh, every major poll," by an average of 12.8 points, says Joe Garofoli in the San Francisco Chronicle. And "Palin can read poll numbers as well as any politician," says B. Daniel Blatt at Gay Patriot. Heck, in one poll, three-quarters of Republicans didn't want her to run.

2. Christie sunk her chances
If Palin had run, she might have become the most credible conservative alternative to Mitt Romney, says Allahpundit at Hot Air. That's largely because fellow conservative Herman Cain won't last, and Texas Gov. Rick Perry is fading fast. But Palin would have had a hard time beating the deep-pocketed Romney in a two-way race. "Once Christie decided not to get in and split the centrist vote with Romney, there was no obvious path for her (which may explain the timing of her announcement today)."

3. Palin really does think she'll be more influential out of the race
In retrospect, it's pretty clear that Palin has long been campaigning to be "Queen of the Tea Party," not president of the United States, says Molly Ball at The Atlantic. Just look at the evidence: Widely covered tours with the Tea Party Express; the "hagiographic movie, The Undefeated, that cast her in that royal mother role"; and her repeated criticisms "of the entire political establishment," including some Republicans. Sitting out the race lets Palin "remain a kingmaker," says Gay Patriot's Blatt. "Her endorsement could well help decide the contest."

4. She doesn't want the pay cut
Joining the race would have meant losing her $1 million annual contract with Fox News, says Joe Gandelman at The Moderate Voice, a factor that surely figured into her decision. Then again, says The Atlantic's Ball, it's not clear she'll even "continue to be employed by Fox News" after making her announcement elsewhere (on an ABC affiliated radio station), a "potentially telling snub."

5. Palin is saving her fire for 2014, or 2016, or...
"In true Palin form, her announcement does leave the door open for plenty of speculation," says Joe Coscarelli at New York. "Notice how she makes it clear that she 'will not be seeking the 2012 GOP nomination,'" saying nothing about 2016. It's true, says Hot Air's Allahpundit, that Palin is just "47 years old, fully 25 years younger than McCain was when he was nominated three years ago." There's clearly "no rush." If she challenged Sen. Mark Begich (D-Alaska) in 2014 and won, that "would be a huge first step back towards national viability down the road." Hey, if she backs the winning Republican presidential candidate this year, says Dan Riehl in Riehl World View, she might even wind up as energy secretary.