Bernie Sanders
© Reuters / Carlos Barria
He's Berning out.

​Sen. Bernie Sanders' support in neighboring New Hampshire, where he trounced Hillary Clinton in the 2016 primary election, has fallen 6 percentage points since April, a survey found.

The Vermont independent's 10 percent level of support in the Granite State left him in fifth place behind Democratic presidential contenders Joe Biden, who leads with 21 percent, Sen. Kamala Harris at 18 percent, Sen. Elizabeth Warren with 17 percent and Mayor Pete Buttigieg at 12 percent, ​according to the Saint Anselm College Survey Center poll released Monday.

Sanders, who beat Clinton in the February 2016 primary by 22 percentage points, scored 16 percent support in April's survey.

Biden managed to retain his lead despite a 2 percentage-point drop from April, but Harris and Warren have risen in the poll after strong showings in last month's Democratic debate.

Harris more than doubled her support from April and Warren increased hers by 8 percentage points.

Buttigieg, the mayor of South Bend, Ind., has remained stable, but Sen. Cory Booker and former Rep. Beto O'Rourke have seen their support disappear.

New Hampshire Institute of Politics executive director Neil Levesque called Biden's narrow lead in the polls "precarious" because his support comes from older and more conservative voters.

​"Among voters that are 'extremely interested' in the upcoming presidential election, Harris and Warren are tied at 2​0 percent​ support, leading Biden at 19​ percent," he said. "Among 'extremely' and 'very interested' voters, Harris leads with 19​ percent support to Biden's 18​ percent and Warren's 17​ percent."

​The survey was conducted between July 10 and 12 and questioned 351 registered voters in New Hampshire. It has a plus/minus 5.2 percentage-point margin of error.