Sanders cuts into Clinton's lead in Iowa, survey finds

Hillary Clinton is the top choice for a majority of likely Iowa caucusgoers, according to a new survey published Thursday by Quinnipiac University.

Fifty-two percent of poll respondents say they would support Clinton, the former U.S. secretary of state and senator, in Iowa's first-in-the-nation presidential vote. U.S. Sen. Bernie Sanders, I-Vermont, follows at 33 percent.

The result is the first time Clinton's support has fallen below 60 percent in a poll conducted by Quinnipiac, and represents and substantial bump for Sanders, who in a May survey polled at just 15 percent.

Three percent of respondents say they would support former Maryland Gov. Martin O'Malley on caucus night, and 7 percent favor Vice President Joe Biden — who has not formally entered the race and done little to indicate that he will.

Clinton, Sanders and Biden all enjoy high favorability ratings, while other candidates remain widely unknown among the Iowans most likely to participate in the caucuses. Clinton is widely seen as honest and trustworthy, the poll found.

The Quinnipiac University Poll surveyed 761 likely Iowa Democratic Caucus participants between June 20 and 29, and has a margin of error of +/- 3.6 percentage points.

Here are the full poll results on likely caucusgoers' top choices:

Hillary Clinton 52%

Bernie Sanders 33%

Joe Biden 7%

Martin O'Malley 3%

Jim Webb 1%

Lincoln Chafee 0%

Don't know 5%