WASHINGTON (Reuters) - Hillary Clinton has retaken the lead among likely Democratic voters in Iowa, a key early voting state in the nomination race ahead of the 2016 presidential election, a Quinnipiac University opinion poll released on Friday found.
The survey of 592 likely Democratic participants in the Iowa caucus showed 51 percent backed the former U.S. secretary of state compared with 40 percent who supported her rival, U.S. Senator Bernie Sanders of Vermont.
Last month, a Quinnipiac poll found the two liberals neck-and-neck, with Sanders at 41 percent and Clinton at 40 percent. Her lead this month is within the poll's margin of error of plus or minus 4.1 percentage points.
On Thursday, a similar Quinnipiac poll of Republican presidential contenders showed retired physician Ben Carson outpacing businessman and TV personality Donald Trump in the Midwestern state.
While the poll offers a glimpse into just one of 50 U.S. states, Iowa's February caucus can help set the stage early in the campaign for the parties' eventual nominees for the November 2016 election. However, a win there does not cement the nomination as past winners have later stumbled and lost their party's support.
Sanders, a self-described Democratic socialist, has been steadily pressuring Clinton, who has been dogged by questions over her use of private email rather than government email while leading the Department of State. Reuters/Ipsos polling, as of Oct. 20, showed nearly half of self-declared Democrats supported Clinton and 26 percent chose Sanders.
Quinnipiac's telephone survey was taken Oct. 14-20, before U.S. Vice President Joe Biden announced he would not seek the presidency.
Peter Brown, assistant director of the university's polling unit, said Clinton's rise in Iowa likely reflected her solid showing at the Oct. 13 Democratic debate as well as support among women.
"The debate seemed to reverse that trend and once again she is the leader of the pack in Iowa," he said in a statement.
The poll also showed that among likely female Democratic caucus participants in Iowa, 59 percent favored Clinton compared with 33 percent for Sanders. More males likely to be caucus-goers backed Sanders over Clinton, 51 percent to 39 percent.
(Reporting by Susan Heavey; Editing by Jeffrey Benkoe)