WASHINGTON - South Bend Mayor Pete Buttigieg holds a clear lead among Democratic presidential candidates in Iowa, the state that will hold the first nominating contest in February, a new Des Moines Register/CNN/Mediacom opinion poll showed on Saturday.

Buttigieg's support climbed to 25%, a 16-point increase since the previous survey in September, CNN reported.

It said there was a close three-way battle for second with Massachusetts Senator Elizabeth Warren at 16%, and former Vice President Joe Biden and Vermont Senator Bernie Sanders each at 15%.

Since September, Warren dropped six percentage points and Biden slipped five points, while Sanders gained four points, CNN said.

Buttigieg, the 37-year-old mayor of South Bend, Indiana, told the network the news was encouraging and his campaign felt growing momentum in the farm state, but there was "still a lot of work to do" in increasing his name recognition there.

Buttigieg also led Democratic presidential candidates in Iowa in a Monmouth University poll released on Tuesday.

A New York Times/Sienna poll released earlier this month also showed Buttigieg's support surging in Iowa, but still behind Warren and Sanders. Nationally, he does not fare nearly as well, averaging around 8% in polls.

Buttigieg's campaign is betting a strong finish in the Iowa caucus on Feb. 3 will help quell questions about whether he is ready for the big stage, and persuade reluctant black and Hispanic voters to give him a second look.

Buttigieg, 37, has invested heavily in Iowa from the start.

His campaign has more than 100 staffers and 20 offices in the state, among the most of any candidate.

Buttigieg finished the third quarter with $23.4 million in campaign cash on hand, ranking third behind Warren and Sanders at $25.7 million and $33.7 million, respectively. Biden had $8.9 million, forcing his campaign to abandon a promise to reject support from political action committees.