De Blasio says he feels he's contributed all he can "to this primary election." He tells MSNBC's "Morning Joe" show "it's clearly not my time."
RELATED: Bill de Blasio through the years
NYC Mayor Bill de Blasio through the years
NYC Mayor Bill de Blasio through the years
New York City Mayor Bill de Blasio speaks regarding the U.S. President Donald Trump's federal budget proposal at the City Hall in New York, U.S., March 16, 2017. REUTERS/Lucas Jackson
New York City Mayor Bill de Blasio poses next to the "Fearless Girl" statue in New York, U.S., March 27, 2017. REUTERS/Shannon Stapleton
New York City Mayor Bill de Blasio speaks during a dedication ceremony for "Lunchbox", the first of eventually 20 new ferry boats of the 'NYC Ferry' service in Brooklyn, New York, U.S., April 17, 2017. REUTERS/Mike Segar
New York Mayor Bill de Blasio speaks regarding the U.S. President Donald Trump's federal budget proposal with New York Police Department Commissioner James O'Neill (R) at city hall in New York, U.S., March 16, 2017. REUTERS/Lucas Jackson
Bill de Blasio, New York City's new public advocate, at a press conference where the health employees union 1199 SEIU announced a donation of $1 million to UNICEF for Haiti relief. (Photo by James Leynse/Corbis via Getty Images)
NEW YORK - SEPTEMBER 01: Actor Steve Buscemi attends a press conference where he announced his endorsement for Bill de Blasio (right) for New York City public advocate at City Hall on September 1, 2009 in New York City. (Photo by Jemal Countess/Getty Images)
NEW YORK - SEPTEMBER 01: Bill de Blasio speaks at a press conference with UFA President Steve Cassidy (right) where he accepted the endorsement for New York City public advocate at City Hall on September 1, 2009 in New York City. (Photo by Jemal Countess/Getty Images)
Rachael Ray (L) and Bill de Blasio attend the New York City Coalition Against Hunger's 'New York City...A Future Hunger-Free Town' Reception at Bayard's on May 3, 2011 in New York City. (Photo by Rob Kim/FilmMagic)
NEW YORK - OCTOBER 22: New York City Council members Letitia James (L) and Bill De Blasio sit in Manhattan Supreme Court to file a lawsuit in an attempt to block a vote in the New York City Council to lift term limits October 22, 2008 in New York City. New York City Mayor Michael Bloomberg is trying to seek a third term in office by overturning a referendum that set term limits for the mayor and council members to two terms. (Photo by Marc A.Hermann-Pool/Getty Images)
NEW YORK, NY - DECEMBER 05: New York City Public Advocate Bill de Blasio and his wife Chirlane Blasio attend the launch of the Canon Boutique at Willoughby's on December 5, 2011 in New York City. (Photo by Steve Mack/Getty Images)
BROOKLYN, NEW YORK, USA- DECEMBER 30, 2012- Bill de Blasio and his son Dante DeBlasio at the Donut Shop in Park Slope, Brooklyn. (Photo by Katie Orlinsky/Getty Images)
Bill de Blasio and his wife Chirlane MCray, his son Dante DeBlasio, and his daughter Chiara DeBlasio outside her home in Park Slope, Brooklyn. Katie Orlinsky for the Wall Street Journal.
REV. AL SHARPTON (center), CHRISTINE QUINN (far left), BILL THOMPSON, BILL DE BLASIO and JOHN LIU (far right) with residents at Lincoln Houses in East Harlem on 135th Street at a press conference for mayoral sleepover. Photo: Kevin C. Downs/NurPhoto (Photo by NurPhoto/Corbis via Getty Images)
NEW YORK, NY - AUGUST 14: Mayoral candidates Anthony Weiner and Bill de Blasio attend The New York City Mayoral Forum on Cultural Sensitivity & Tolerance at the Museum of Tolerance on August 14, 2013 in New York City. (Photo by Taylor Hill/Getty Images)
NEW YORK, NY - APRIL 09: New York City Public Advocate and mayoral candidate Bill de Blasio speaks at a political forum on a boat in Manhattan on April 9, 2013 in New York City. Six mayoral candidates spoke at the Metropolitan Waterfront Alliance's 2013 Waterfront Conference ahead of the November 2013 mayoral election. (Photo by Mario Tama/Getty Images)
NEW YORK, NY - JUNE 12: Mayor of New York City, Bill de Blasio attends the 2014 Wildlife Conservation Society Gala at Central Park Zoo on June 12, 2014 in New York City. (Photo by Noam Galai/WireImage)
Paris Mayor Anne Hidalgo and New York City Mayor Bill de Blasio address a press conference after a meeting at City Hall in New York, May 30, 2014. Anne Hidalgo is on a two-day visit to New York. AFP PHOTO/Emmanuel Dunand (Photo credit should read EMMANUEL DUNAND/AFP/Getty Images)
NEW YORK, NY - OCTOBER 01: (L-R) NYC Mayor Bill de Blasio and filmmaker Spike Lee attend Al Sharpton's 60th Birthday Celebration at Four Seasons Hotel New York on October 1, 2014 in New York City. (Photo by Johnny Nunez/WireImage)
NEW YORK, NY - SEPTEMBER 30: New York City Mayor Bill de Blasio (R) and Department of Labor Secretary Tom Perez speak privately at a press conference before signing an executive order raising the living wage law on September 30, 2014 in New York City. Under the new living wage law, which takes effect today, employees of companies that receive more than $1 million in subsidies from the city government will need to pay their employees between $11.50 - $13.13 an hour, depending on whether or not the employee receives benefits. The law is expected to effect thousands of people working in industries from retail to fast food. (Photo by Andrew Burton/Getty Images)
NEW YORK, NY - OCTOBER 13: New York City Mayor Bill de Blasio marches in the annual Columbus Day parade on October 13, 2014 in New York City. Organized by the Columbus Citizens Foundation, the parade is billed as the world's largest celebration of Italian-American heritage and culture and has been run since 1929. The parade runs from 44th Street to 72nd Street and is also used as a showcase for local politicians. (Photo by Spencer Platt/Getty Images)
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The mayor had announced his presidential run by heading to the Statue of Liberty, where he said the country is in an "identity crisis" around immigration, which he called "the founding and unifying element of the American experience."
"We are figuring out who we are," he said then. "There are American values we need to return to and fight for in order to achieve our greatest potential."
On his campaign's first day, he dived into an insult match with President Donald Trump.
"He's a con artist. I know his tricks. I know his playbook," the mayor said.
Trump tweeted that de Blasio was "considered the worst mayor in the U.S."
The Republican president said, "He is a JOKE, but if you like high taxes & crime, he's your man. NYC HATES HIM!"
When de Blasio took office in 2014, he seemed briefly poised to become a leading voice for an emerging left wing of the Democratic Party. His central message was fighting income inequality, a theme he hit in the video announcing his presidential candidacy.
"There's plenty of money in this world. There's plenty of money in this country. It's just in the wrong hands," he said.
Liberal enthusiasm faded during his first term, partly because of political missteps at home and the emergence of bigger names elsewhere. He faced obstacles trying to distinguish himself in a crowded field.