The CNN/Des Moines Register/Mediacom poll showed Buttigieg with 25 percent support, a 16 percent increase over his numbers in the September version of the poll.
Warren's support has dropped six percentage points from the September CNN/DMR/Mediacom poll, while Biden's backing has slipped five percentage points.
A Monmouth University poll released Tuesday pegged Buttigieg at 22 percent, Biden at 19 percent, Warren at 18 percent and Sanders at 13 percent.
Buttigieg's support jumped 14 percentage points compared to Monmouth’s last survey in August, while Biden’s dropped seven percentage points, Warren’s edged down two percentage points, and Sanders jumped five percentage points from the August survey.
Among Iowa caucusgoers, 63 percent say Buttigieg's views are about right, while only seven percent say they are too liberal and 13 percent say they are too conservative.