The presidential campaign of Sen. Bernie Sanders (I-Vt.) submitted a letter to the New York State Board of Elections on Sunday challenging a looming decision on whether to keep him on the ballot for the state’s primary.

Sanders formally suspended his campaign earlier this month, but said that he planned to stay on the ballot in upcoming primaries in order to maximize his influence on the Democratic Party’s platform and rules.

Five days later, New York Gov. Andrew Cuomo (D) signed a budget bill with an obscure provision authorizing the state’s board of elections to remove from the primary ballot those candidates who have withdrawn from the presidential campaign.

MANDEL NGAN/AFP/Getty Images Though he's withdrawn from the presidential race, Sen. Bernie Sanders still wants the chance to shape Democratic Party rules at the convention.

Malcolm Seymour, an attorney representing the Sanders campaign, argued in the letter to the board that the provision should not apply to Sanders “retroactively,” since he might have acted differently if it had been in effect when he decided to suspend his campaign.

“The retroactive application of [the change in election law] would severely impact Senator Sanders’ core substantive rights,” Seymour wrote in the letter obtained by HuffPost. “Because of the severity of this potential deprivation, the presumption against retroactive application must operate with maximum force.”

Seymour further noted that the new law merely states that the board of elections “may,” rather than “must,” decide to remove from the ballot candidates who have ended their campaigns for the nomination.

The legislature would not have given the Board this discretion if the legislature had not anticipated that situations would arise in which a candidate’s removal would be improper. Malcolm Seymour, a lawyer for the Sanders campaign

“The legislature would not have given the Board this discretion if the legislature had not anticipated that situations would arise in which a candidate’s removal would be improper,” the lawyer said. “This is clearly one such situation ― Senator Sanders has publicly stated that he wishes to remain a candidate and has formally objected to his removal.”

Seymour noted that no interested party ― including former Vice President Joe Biden, the Democratic National Committee and the New York State Democratic Party ― has asked the board of elections to remove Sanders.

“His involuntary erasure from the ballot, on grounds of a law that was not in effect when he announced his campaign’s limited suspension, would sow needless strife and distrust, impeding Senator Sanders’ efforts to unify the Democratic Party in advance of November elections,” Seymour added.

HuffPost reported last Tuesday that the two Democratic members of the board, co-chair Douglas Kellner and commissioner Andrew Spano, were due to meet the following day to decide on Sanders’ potential removal. The two men must reach a unanimous decision in order to cut Sanders from the ballot. Prior to that meeting, Kellner told HuffPost that he thinks he is legally obligated to remove Sanders. Spano expressed ambivalence, however, weighing the inconvenience to county governments against the desire of Sanders supporters for a “voice at the convention.”

Following HuffPost’s reporting, which brought to light the complaints of a select group of local Sanders supporters, a larger contingent of Sanders activists and allies escalated their calls to keep him on the ballot. The board of elections announced that it was delaying its decision until Monday.

The Sanders campaign’s letter to the board on Sunday marks its first official intervention into the deliberations in New York.

Remaining on the ballot in New York is a priority for Sanders because he hopes to win enough convention delegates nationwide for his allies to receive at least 25% of the seats on the three key convention committees in August: those concerning rules and bylaws, the party platform, and convention credentials. A quarter share of the committees’ membership ensures that Sanders’ bloc will have the opportunity to submit a minority report to the convention floor for a vote on matters such as permanently disempowering the party insiders and elected officials known as “superdelegates.” (Sanders’ allies previously helped shepherd through rule changes barring the superdelegates from voting for a presidential candidate on the first convention ballot, but that move applies only to the 2020 nominating contest.)

It is unusual, if not unprecedented, for presidential candidates to continue to compete for convention delegates after formally suspending their campaign.

But the Biden campaign, which believes that mollifying Sanders’ base would help the former vice president defeat President Donald Trump in November, has already shown a willingness to negotiate with Sanders over delegate allocation. The two campaigns are in talks over how to divvy up the one-third of convention delegates awarded based on statewide primary and caucus results. Normally, candidates who are no longer running can hold on to their share of the two-thirds of delegates awarded based on their primary performance in each congressional district but are not eligible to keep statewide delegates they’ve won.

Currently, there are 11 Democratic presidential candidates who remain on the ballot in New York: Biden; Sanders; Sens. Michael Bennet (Colo.), Amy Klobuchar (Minn.) and Elizabeth Warren (Mass.); billionaire businessmen Mike Bloomberg and Tom Steyer; former South Bend, Indiana, Mayor Pete Buttigieg; former Massachusetts Gov. Deval Patrick; Rep. Tulsi Gabbard (Hawaii); and entrepreneur Andrew Yang. Aside from Sanders, none of the other candidates who have dropped out of the race have asked to remain on the ballot. Should the board decide to remove all of those candidates, the state’s presidential primary would be canceled. Some 20 of the state’s 62 counties would not hold any primary elections at all as a result.

In late March, Cuomo postponed the New York presidential primary from April 28 to June 23 because of the coronavirus pandemic. That made the presidential primary coincide with New York’s congressional and state legislative primaries. Some left-wing activists in the state hoped that Sanders’ continued presence on the ballot would benefit progressive candidates running for lesser offices who might get the support of Sanders voters who would not otherwise turn out. Those activists now fear the effort to remove Sanders is motivated by a desire to undermine primary challengers.

Larry Cohen, a top Sanders ally and chairman of Our Revolution, which emerged from Sanders’ 2016 bid, is urging the board of elections to give Sanders supporters in New York a chance to make their views known.

“Your mission is democracy. Your mission is to let people vote, not to come up with some scheme to stop them,” he said of the board’s responsibility.

New York state will face issues of its own if it decides to remove Sanders. It will have to get the Democratic National Committee’s approval for a new plan to allocate convention delegates who would otherwise be awarded based on the outcome of the primary. If necessary, Cohen told HuffPost, he is prepared to try to challenge the legitimacy of the state’s delegates in the convention’s credentials committee.

Cohen, who previously led the Communications Workers of America union, also cautioned Biden that Sanders’ removal could hinder efforts to rally the Democratic Party’s progressive wing behind the presumptive nominee.

“This is not the way you build unity,” Cohen said.