Since September, Buttigieg has risen 16 percentage points among Iowa’s likely Democratic caucusgoers, with 25% now saying he is their first choice for president. For the first time in the Register’s Iowa Poll, he bests rivals Joe Biden, Bernie Sanders and Elizabeth Warren, who are now clustered in competition for second place and about 10 percentage points behind the South Bend, Indiana, mayor.

Warren, a U.S. senator from Massachusetts, led the September Iowa Poll, when 22% said she was their first choice. In this poll, her support slips to 16%. Former Vice President Biden, who led the Register’s first three Iowa Polls of the 2020 caucus cycle, has continued to slide, falling 5 percentage points to 15%. Sanders, a U.S. senator from Vermont, also garners 15% — a 4 percentage point rise…

More respondents — 30% now, compared with 20% in September — say they have a first choice and their minds are made up. That still leaves ample opportunity for more surges and slides in the two-and-a-half months before the caucuses: 62% say they have a first choice but could still be persuaded, 1% are unsure and 7% have not made a first choice. In September, 16% of caucusgoers said they had not made a first choice.