Joe Biden’s (D) national lead in the Democrat primary race is narrowing, according to a Reuters/Ipsos poll released on Tuesday.

The survey, taken March 13-16, 2020, showed the former vice president losing his double-digit lead over Sen. Bernie Sanders (I-VT), who trails the former vice president in current pledged delegate totals.

“If the 2020 Democratic presidential primary election were held today, and you had to choose from the list of candidates below, for whom would you vote?” the survey asks.

Biden leads Sanders among registered Democrat voters, 48 percent to 39 percent. Biden led in the same poll one week ago by 21 percentage points.

Two percent of Democrat voters indicated support for Rep. Tulsi Gabbard (D-HI), and eight percent said they “don’t know” whom they would support.

The sample size and margin of error were not immediately available.

The news comes as voters in three more states, Arizona, Florida, and Illinois, cast their ballots for their preferred candidate in Tuesday’s election.

Biden needs 50.4 percent of the remaining delegates in order to secure the Democrat nomination on the first ballot. Sanders faces more of an uphill battle, needing 57.5 percent of the remaining pledged delegates, according to NPR’s delegate tracker.

The latest RealClearPolitics average shows Biden leading Sanders by over 20 percentage points nationally.