Sanders edges Clinton 41% to 40% in a new survey by Quinnipiac University
, overtaking the former secretary of state as she continues to be dogged by questions about her use of a private email server when she was in public office. Sanders trailed her by 21 points the last time Quinnipiac surveyed the field two months ago, and that margin has more or less held in surveys in Iowa throughout the summer -- until recently.
Vice President Joe Biden, who is mulling a late entry into the race, collected 12% support in Thursday's poll.
For Clinton, the poll will come as a sharp reminder of her 2008 race, when she also faltered in Iowa despite her once-inevitable nominee status. Clinton also trails Sanders in New Hampshire polling, the second nominating state.
Clinton still maintains solidly double-digit leads in national polls and remains the overwhelming favorite of the Democratic establishment. But Sanders' rise has injected new drama to the Democratic race.
"He is the candidate of the Democratic left, against his own party's bosses and their prized presidential candidate," explained Quinnipiac pollster Peter A. Brown. "Sanders has seized the momentum by offering a message more in line with disproportionately liberal primary and caucus voters."
Even if she were to ultimately lose Iowa and New Hampshire, Clinton's financial and political power could make her formidable in the states that vote next, especially in the south. But her ratings on key personality questions are giving some Democrats pause. Clinton chose to issue a formal apology this week for some of her email practices, but 30% of Democratic voters responding to the poll said they do not find her honest and trustworthy. Only 4% said the same was true of Sanders and 5% of Biden.
Former Maryland governor Martin O'Malley earned 3% support in the poll, and former Virginia senator Jim Webb won 1%. Lincoln Chafee of Rhode Island did not register in the survey.
Quinnipiac polled 832 likely Iowa caucus-goers between Aug. 27-Sept. 8 for a margin of error of plus or minus 3.4 percentage points.