(CNN) South Bend, Indiana, Mayor Pete Buttigieg joined the leaders of the Democratic race for president in Iowa, up 14 percentage points since August, according to a new Monmouth University poll of likely caucusgoers out Tuesday.

Buttigieg garnered 22% support, in the top tier with former Vice President Joe Biden (19%) and Massachusetts Sen. Elizabeth Warren (18%). Vermont Sen. Bernie Sanders also made gains from Monmouth's August poll, but with 13%, fell outside of the top three status in Iowa.

Because their support falls within the margin of error, there is no clear leader in the Iowa poll, with Buttigieg, Warren, and Biden making up the top tier of candidates.

Minnesota Sen. Amy Klobuchar received 5% support from likely Democratic Iowa caucusgoers, followed by California Sen. Kamala Harris, businessmen Tom Steyer and Andrew Yang with 3% each, and New Jersey Sen. Cory Booker and Hawaii Rep. Tulsi Gabbard with 2%. No other candidate received above 1% support in the poll.

Harris was down from 12% in August, reflecting other polls showing her dipping nationally and in key states.

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