Sen. Bernie Sanders's 2020 Democratic presidential campaign on Thursday urged New York Gov. Andrew Cuomo to sign legislation that would extend the state's party registration deadline and avoid a repeat of 2016, when many would-be primary voters belatedly discovered they failed to comply with the state's onerous process.

Under the current rules, New Yorkers only have until Oct. 11 to register as Democrats to vote in the state's 2020 primary, which is not until April 28—more than six months apart. New York is a closed primary state, meaning only registered Democrats can vote in the presidential primary election.

"There is no excuse for letting this legislation languish for three months when the current party affiliation deadline is fast approaching."
—Faiz Shakir, campaign manager for Sen. Bernie SandersIn a letter to Jim Roosevelt and Lorraine Miller, co-chairs of the DNC Rules and Bylaws Committee, Sanders campaign manager Faiz Shakir said the DNC should pressure Cuomo to "expeditiously" sign legislation that would extend the state's party registration deadline to Feb. 14.

The New York legislature passed the bill in June.

"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. "There is no excuse for letting this legislation languish for three months when the current party affiliation deadline is fast approaching."

Shakir said the DNC must "consider appropriate sanctions" if Cuomo fails to sign the bill before Oct. 11, which would prevent the changes from taking effect for the 2020 primary. Rich Azzopardi, a senior adviser to Cuomo, said the governor intends to sign the legislation.

"The current deadline to change isn't until Oct. 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," Azzopardi told the New York Daily News.

Melissa DeRosa, secretary to Cuomo, wrote on Twitter in response to the Sanders campaign's letter that the governor plans to sign the bill "before the October 11 deadline."

As Politico's Holly Otterbein reported Thursday, many Sanders supporters were outraged in 2016 after "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."

Sanders lost the 2016 New York primary to Hillary Clinton by 16 points.

"In 2020," Otterbein wrote, "Sanders's campaign is determined to avoid a repeat."