Mr. de Blasio, the former New York City mayor, had signaled for months that he planned to run for governor, but he faced long odds in a crowded Democratic primary.
Bill de Blasio, the former mayor of New York City, said on Tuesday that he would not run for governor of New York, as he had been widely expected to do.
Mr. de Blasio, a Democrat who served two terms in office, had signaled for months that he was planning a campaign, saying repeatedly that he did not feel ready to leave public service.
He made the announcement in a video posted on Twitter, highlighting the accomplishments of his mayoral tenure before announcing that he would not be joining the governor’s race.
“No, I am not going to be running for governor in New York State,” Mr. de Blasio said, standing on the street outside his Brooklyn residence. “But I am going to devote every fiber of my being to fight inequality in the state of New York.”
Mr. de Blasio then hinted that he would have more to say about his future in the coming days.
He declined to enter a crowded Democratic primary field, with the incumbent, Gov. Kathy Hochul, facing challenges from Jumaane D. Williams, the city’s public advocate, and Representative Tom Suozzi of Long Island.
A Siena College poll released earlier on Tuesday showed Ms. Hochul with a significant lead over her competitors and potential competitors, including Mr. de Blasio. She earned the support of 46 percent of Democrats polled, while Mr. de Blasio had 12 percent, Mr. Williams had 11 percent and Mr. Suozzi had 6 percent. Across party lines, 45 percent of voters polled said they viewed Ms. Hochul favorably. The poll had a margin of error of plus or minus 4 percentage points.
Ms. Hochul has also outpaced her competitors in fund-raising, having raised a record-breaking $21.6 million so far.
For months, Mr. de Blasio had signaled that he would run. He appeared on MSNBC frequently and promoted a statewide education plan. He was also sounding out trusted former aides about joining a campaign, and he made overtures to labor leaders.
Mr. de Blasio had said that he was not deterred by polls that showed him badly trailing his rivals.
“I have a long, rich history of being an underdog,” he said.
New York City mayors have had a difficult time attaining higher office. The last one to do so was John T. Hoffman, who was elected governor in 1868. Many mayors have run for president, including John V. Lindsay in 1972 and, more recently, Michael R. Bloomberg and Mr. de Blasio himself.
Mr. de Blasio had planned to focus on his popular universal prekindergarten policy, his handling of the pandemic and his focus on aggressive vaccine mandates. He also used his final weeks in office to argue that he had reduced inequality, which he set out to do when he was elected in 2013 on a message that he would address the imbalance that had led to a “tale of two cities.”
In his video on Tuesday, Mr. de Blasio also acknowledged some of his less popular moments as mayor, including accidentally killing a groundhog and driving out of his way to visit his preferred gym in Park Slope.
“Now I made my fair share of mistakes,” Mr. de Blasio said. “I was not good with groundhogs at all. I probably shouldn’t have gone to the gym. But you know what, we changed things in this town.”
