Pete Buttigieg, mayor of South Bend, Indiana, topped the latest poll of likely Democratic voters in Iowa, the first state in the nation to weigh in, via caucus, on who should be the blue party's choice for president.

The moderate mayor supported by 25 percent of respondents was followed by Sen. Elizabeth Warren of Massachusetts with 16 percent; former Vice President Joe Biden, 15 percent; Sen. Bernie Sanders of Vermont, 15 percent; and Sen. Amy Klobuchar of Minnesota, 6 percent.

The poll of 500 likely caucus-goers was conducted by the Des Moines Register, CNN and Mediacom.

Buttigieg was described by the Register as having "rocketed to the top" of the crowded Democratic field of about 19 candidates. His standing has risen 16 percentage points since September, according to its polling.

Iowa will hold caucuses Feb. 3, making it the first state to officially say who should represent the Democratic Party in 2020. It will be followed by the New Hampshire primary on Feb. 11, the Nevada primary Feb. 22 and South Carolina on Feb. 29.

The poll didn't seem to give a lot of hope to the billionaires in the field, including California tech entrepreneur Tom Steyer, who registered 3 percent support, and former New York Mayor Michael Bloomberg, a late entry to the field, who rang up 2 percent.

Sen. Cory Booker of New Jersey, Rep. Tulsi Gabbard of Hawaii and Sen. Kamala Harris of California all ended up in the middle of the pack, each with 3 percent support.

The poll was conducted Nov. 8 to 13 and has a margin of error of plus or minus 4.4 percentage points.