(CNN) Massachusetts Sen. Elizabeth Warren, South Bend, Indiana Mayor Pete Buttgieg, Vermont Sen. Bernie Sanders, and former Vice President Joe Biden make up a top tier in the race for the Democratic nomination in Iowa, according to a new poll from Quinnipiac University.

Warren receives 20% support among likely Democratic caucusgoers, followed by 19% for Buttigieg, 17% for Sanders and 15% for Biden.

Behind the top tier are Minnesota Sen. Amy Klobuchar with 5% support, California Sen. Kamala Harris with 4%, and Hawaii Rep. Tulsi Gabbard, businessman Tom Steyer, and businessman Andrew Yang at 3% each. No other candidate receives above 1% support.

The results mark the fourth qualifying poll for the November DNC debate at 3% or higher for Gabbard, meaning she will qualify for the debate stage. The poll also means Klobuchar has met the polling criteria for the December debate. She is the sixth candidate to meet those higher standards.

The new poll mirrors a Siena College/New York Times Upshot poll from last week, which showed a similarly tight four person race with Warren at 22%, Sanders at 19%, Buttigieg at 18% and Biden at 17%.

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