"I'm pulling out and I'm going to concentrate all my time and energy in the next week working to defeat the recall because I realize that's the only way to defeat Arnold Schwarzenegger," Huffington said on CNN's Larry King Live.
But Huffington declined to specifically endorse Bustamante, merely urging her supporters to "vote strategically" in an effort to stop a Republican takeover of California. She urged people to vote against the recall and then consider their options for the second half of the Oct. 7 ballot.
Van Jones, Huffington's chief grass-roots organizer, said she was trying "to position herself so she can maximize opposition to the Schwarzenegger coup."
Huffington, a 53-year old columnist and TV pundit who transformed herself from Republican to fiery populist, drew a loyal following on the Internet and on the campaign trail.
But in a CNN-USA Today-Gallup poll released Sunday, she had only 2 percent support among the most likely voters, compared with 40 percent for Schwarzenegger and 25 percent for Bustamante.
Asked about Huffington's decision at a campaign stop, Democrat Davis praised her and wished her well. "I think Arianna Huffington has brought some wisdom and some clarity to the second question on this ballot, and I believe she's made a contribution to the dialogue that has begun over these last 70 to 75 days," he said.
Huffington had repeatedly criticized Bustamante's acceptance of big donations from Indian casino interests. But she called it "wonderful news" Sunday when Bustamante made a surprise endorsement of her initiative to publicly finance state election campaigns.
"As you know, I believe in conversions, and I believe in redemption," said Huffington, who called herself a "recovering Republican" after her divorce from wealthy GOP Senate candidate Michael Huffington.
In recent days, the recall race has focused on the match of Davis vs. Schwarzenegger, the leading Republican replacement candidate.
GOP state Sen. Tom McClintock had 18 percent in the Gallup poll, but he has repeatedly vowed to stay in the race despite pressure to pull out and avoid splitting the Republican vote.
The poll showed 63 percent of "probable" voters were in favor of removing Davis. Other polls depict a much tighter race on the recall issue and among the replacement candidates.
Green Party candidate Peter Camejo, who had 5 percent in the Gallup poll, said Huffington called him Sunday to let him know she was considering getting out of the race.
"I advised her against it," said Camejo, who early in the campaign had an unofficial pact with Huffington that one would drop out if the other appeared close to victory. Camejo said he has no intention of withdrawing.