Hillary Clinton has the support of nearly half those planning to vote in California's Democratic primary, according to a new Field Poll.
The New York senator's lead has grown since the spring, and 49 percent of likely primary voters in the state now favor her, the survey showed.
Illinois Sen. Barack Obama is far behind, with 19 percent, and former North Carolina Sen. John Edwards is favored by 10 percent.
The poll also tested how the Democrats would fare in hypothetical matchups against Republicans.
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Both Clinton and Obama lead the top Republicans—former New York City Mayor Rudy Giuliani, former Massachusetts Gov. Mitt Romney, Arizona Sen. John McCain and former Tennessee Sen. Fred Thompson, who has not yet joined the race.
Edwards also leads Romney, Thompson and McCain. But he is only slightly ahead of Giuliani, researchers found.
The telephone survey of 418 likely Democratic primary voters was taken in English and Spanish from Aug. 3 to 12. It has a sampling error of plus or minus 4.5 percentage points.