The decision Monday by the Democratic commissioners of the state Board of Elections made New York the first state to cancel its presidential primary. It followed a decision by Senator Bernie Sanders of Vermont to end his presidential campaign, effectively conceding the Democratic nomination to former Vice President Joseph R. Biden Jr.

The move Monday angered supporters of Mr. Sanders. They had mounted an email and phone campaign to pressure the Democratic election commissioners to hold the primary so their candidate could amass more delegates to the Democratic National Convention and wield greater influence over the party platform.

[Get the latest news and updates on the coronavirus in the New York region.]

Death counts keep falling in N.Y. and N.J.

Gov. Andrew M. Cuomo of New York said on Monday that 337 more people had died of the virus in New York State, and Gov. Philip D. Murphy of New Jersey reported an additional 106 deaths there.

The one-day tolls were less than half of what the two states were reporting at their peaks.

With both states showing progress in fighting the virus, Mr. Cuomo and Mr. Murphy have begun to offer details on reopening from the lockdowns in the months ahead.