Citing health concerns, Queens District Attorney Richard Brown, who has been in office since 1991 and who previously announced that he would not seek re-election to a new term, said on Thursday that he is stepping down early.

Brown, who has Parkinson's disease, announced that he will resign on June 1 and that his chief assistant, John Ryan, will officially step into his place until a new district attorney is elected.

“It had been my hope that I would be able to finish out this term in office,” Brown, 86, said in the announcement. “Unfortunately, that is not to be. Given the current state of my health and my ongoing health issues, it has become increasingly difficult to fully perform the powers and duties of my office in the manner in which I have done since 1991.”

Gov. Mario Cuomo appointed Brown, a former state Supreme Court justice who served on the Appellate Division, Second Department, to his seat after Brown's predecessor, John Santucci, retired before finishing his term.

Brown was subsequently elected to the seat seven times, often without opposition. Since late last year, an ever-growing field of contenders has stepped up to succeed Brown for what has been widely viewed as a change election for the borough's top law enforcement office.

They are Tiffany Caban, a career public defender who works with New York County Defender Services; Queens Borough President Melinda Katz; Betty Lugo of Lugo & Pacheco, a past president of the Puerto Rican Bar Association; Mina Malik, a former Queens prosecutor who works for the Office of the Attorney General for the District of Columbia; City Councilman Rory Lancman; retired state Supreme Court Justice Gregory Lasak; Jose Nieves, a prosecutor with the New York Attorney General's Office; and Lorelei Salas, commissioner of the city's Department of Consumer Affairs.

All declared candidates are running as Democrats and will face off in a June 25 primary. A general election will be held in November and the first new Queens DA in 28 years will take office in January.

The candidates have all pledged to bring some degree of progressive reform to the Queens DA's office which, under Brown's leadership, has declined to embrace some of the reforms adopted by his counterparts in Brooklyn and Manhattan, such as pulling back on prosecuting some low-level crimes.

The Queens Democratic Party is backing Katz in the race, while Caban has earned the endorsement of city's chapter of the Democratic Socialists of America, a group that has recently displayed its political strength with the election of U.S. Rep. Alexandria Ocasio-Cortez, a member of the organization.

In last year's Democratic primary for a Congressional seat that encompasses portions of the Bronx and Queens, Ocasio-Cortez unseated longtime incumbent Joseph Crowley, who still leads the Queens Democratic Party.   

Lasak has gained the support of several labor unions, including groups representing police lieutenants, court officers and court clerks.

Lancman has gained the endorsement of retired Chief Judge Jonathan Lippman, who was an outspoken advocate for criminal justice reform during his stint as chief judge.