Story highlights

The latest Quinnipiac University poll of Iowa Democrats finds Hillary Clinton growing a lead over Bernie Sanders

Pollsters attribute Clinton's improving numbers to a growing gender gap and her strong debate performance

Washington CNN —  

Hillary Clinton is building a lead over Bernie Sanders in Iowa with help from her debate performance, according to the results from a Quinnipiac University poll released Friday morning.

Clinton holds support from 51% of likely Democratic caucus-goers, compared to 40% who would back Sanders. The results mirror a Bloomberg Politics/Des Moines Register poll released Thursday morning, which found Clinton leading Sanders 48%-41% in Iowa with Vice President Joe Biden out of the race.

The growing divide is due, in part, to a growing gender gap, according to the Quinnipiac results. Men back Sanders over Clinton 51% to 39%, but women support Clinton over Sanders by a greater margin, 59% to 33%.

The last Quinnipiac poll of Iowa Democrats, released last month, found Sanders slightly edging out Clinton, 41% to 40%. Peter A. Brown, assistant director of the Quinnipiac University Poll, attributed the reversal to Clinton’s strong performance at the first Democratic debate earlier this month.

Democrats who watched the debate – about half of those polled – said Clinton easily beat Sanders: 62% picked Clinton as the winner while 31% said Sanders won.

“A strong debate performance doesn’t always translate into better poll numbers, but it sure did for Hillary Clinton. Likely Iowa Caucus participants who watched or listened to the debate scored it 2 – 1 for the former secretary of state,” Brown said in a statement.

Quinnipiac pollsters spoke with 592 likely Democratic caucus attendees from October 14-20, with the results carrying a 4-point margin of error.

CNN’s Jennifer Agiesta contributed to this report.