Bernie Sanders supporters complained in 2016 that New York’s strict party registration deadline locked many of them out of the presidential primary, because state voters must be signed on as Democrats six months before Election Day in order to participate.

In 2020, Sanders’ campaign is determined to avoid a repeat.

Sanders’ campaign manager, Faiz Shakir, sent a letter to the Democratic National Committee on Thursday urging it to demand that New York Gov. Andrew Cuomo approves legislation to extend the state’s voter registration deadline, which is less than a month away.

“In 2016, countless voters across the state of New York were disenfranchised by the state’s arcane and inexcusable early party affiliation deadline — countless voters whose first attempt to engage with the Democratic Party saw them turned away,” Shakir wrote.

Sanders performed well among independents in other states in 2016. But he lost the New York primary, which is closed off to voters who are not Democrats, by 16 points to Hillary Clinton, who represented the state in the Senate for eight years.

The Sanders campaign said the New York Democratic Party had agreed to a plan allowing any voter who changed their party registration by Feb. 14, 2020, to vote in the primary. The New York state Legislature passed a bill this summer to let voters switch their party registration by that date, but Cuomo has not signed it.

A top Cuomo aide said that the governor intends to sign the bill into law. The DNC did not immediately respond to requests for comment.

"The current deadline to change isn't until October 11 and the bill hasn't been sent to us yet, but we fully intend to sign it as this was something that we and the legislature all agree on," said Cuomo senior adviser Rich Azzopardi.

Shakir called on the DNC to "consider appropriate sanctions" if Cuomo does not sign the bill.

Progressives have railed against New York’s party registration deadline for years, saying it disenfranchises younger voters and immigrants in particular.

Cuomo has not endorsed anyone in the presidential primary, but he is an ally of former Vice President Joe Biden.