Former Vice President Joe Biden’s maintaining his lead in Iowa, but Sen. Elizabeth Warren is gaining while Sen. Bernie Sanders’ support plummets, according to a poll released Thursday.

Biden attracted 28 percent of support among voters who will take part in the Iowa caucuses in February 2020 — about the same as his 27 percent in April, the Monmouth University Poll shows.

But Warren has seen her support surge to 19 percent from 7 percent four months ago.

Unlike Warren, Sanders is going in reverse, falling to 9 percent from 16 percent in April.

Among the other Democratic hopefuls, Sen. Kamala Harris is up to 11 percent from 7 percent in April, Mayor Pete Buttigieg has remained stable with 8 percent compared to 9 percent in April, and Sen. Amy Klobuchar has remained steady, falling 1 percentage point from 4 percent in April.

Billionaire investor Tom Steyer, who announced his run last month, gathered 3 percent of support.

Candidates with 2 percent of support include Sen. Kirsten Gillibrand and businessman Andrew Yang.

The remainder poll at 1 percent or less, including Mayor Bill de Blasio, who got 0 percent support.

The poll was conducted between Aug. 1 and 4 and surveyed 681 Iowa voters. It has a plus/minus 4.9 percentage-point margin of error.