Sen. Bernie Sanders of Vermont has moved 1 percentage point ahead of former Secretary of State Hillary Rodham Clinton in Iowa, according to a Quinnipiac University poll of likely Democratic caucus participants in the state where the first votes of the 2016 presidential race will be cast Feb. 1.
In what represents a statistical tie because of the poll's margin of error, Sanders is picked by 41 percent, while Clinton is backed by 40 percent. Vice President Joe Biden, who is still contemplating a potential bid, is the first choice of 12 percent.
The latest numbers represent a drop for Clinton, who continues to confront questions about -- and has now begun to apologize for -- her use of a private email server while secretary of state in the Obama administration. In early July, this same poll had Clinton at 52 percent, Sanders at 33 percent and Biden at 7 percent.
The new survey shows a wide gender gap among Democrats, with Sanders leading Clinton 49 percent to 28 percent among men, while Clinton leads Sanders 49 percent to 35 percent among women.
Sanders and Biden have a higher net favorability rating than Clinton and higher ratings for honesty and empathy, the poll shows.
"Senator Bernie Sanders has become the Eugene McCarthy of 2016," Peter A. Brown, assistant director of the poll, said in a statement referencing the late senator who came on strong just before the 1968 primaries. "Sanders has seized the momentum by offering a message more in line with disproportionately liberal primary and caucus voters."
The survey was conducted Aug. 27 to Sept. 8 and included 832 likely Iowa Democratic caucus participants. It has a margin of error of plus or minus 3.4 percentage points.