FILE PHOTO: Democratic 2020 U.S. presidential candidate and South Bend Mayor Pete Buttigieg speaks at campaign town hall meeting at the University of New Hampshire in Durham, New Hampshire, U.S., October 25, 2019. REUTERS/Brian Snyder/File Photo

WASHINGTON (Reuters) - Pete Buttigieg has pulled to the top of the pack of Democratic presidential candidates in Iowa for the first time after drawing increased support from nearly every demographic group, according to a Monmouth University poll released on Tuesday.

Buttigieg, the mayor of South Bend, Indiana, leapfrogged past former Vice President Joe Biden since Monmouth’s Iowa poll in August to lead in the state that will in February host the first nominating contest. Buttigieg gained 14 percentage points during that time and now has support from about 22% of likely Democratic caucusgoers.

During the same time period, Biden dropped 7 points to 19% support; U.S. Senator Elizabeth Warren of Massachusetts dropped 2 points to 18% support; and U.S. Senator Bernie Sanders of Vermont gained 5 points, with 13% support, according to the poll.

“While he has made nominally bigger gains among older caucusgoers, you really can’t pigeonhole his support to one particular group. He is doing well with voters regardless of education or ideology,” Patrick Murray, director of the Monmouth University Polling Institute, said of Buttigieg’s rise.

But, with fewer than three in 10 likely caucusgoers saying they are firmly decided on their candidate, Murray said the race remains “extremely fluid” ahead of Iowa’s Feb. 3 caucuses, which act as an initial proving ground for U.S. presidential candidates.

Sixteen percent said there is a “high possibility” that they could change their minds and another 37% said there is a moderate possibility they could switch allegiances, according to the poll.

Other candidates in the crowded field of Democrats vying to take on Republican Donald Trump in November 2020 registered single-digit support in Iowa, the Nov. 7-11 telephone poll of 451 likely caucusgoers showed.

The poll also asked voters to pick a second-choice candidate and, when their first and second choices were combined, Buttigieg led the field with 37% support to Warren’s 35% support.

Among Buttigieg’s supporters, Warren and Biden were the second and third choices, with 21% and 20% support respectively. Among Biden’s voters, Buttigieg and Warren were the second and third choices, with 22% and 20% support. Among Warren’s supporters, 33% chose Sanders as their second choice and 26% chose Buttigieg as their third.