New York City Mayor Bill de Blasio Bill de BlasioOVERNIGHT ENERGY: California seeks to sell only electric cars by 2035 | EPA threatens to close New York City office after Trump threats to 'anarchist' cities | House energy package sparks criticism from left and right EPA threatens to close New York City office after Trump threats to 'anarchist' cities New Year's Eve in Times Square to be largely virtual amid pandemic MORE (D), who is running for president, took aim Sunday at the field’s front-runner, former Vice President Joe Biden Joe BidenBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Democratic groups using Bloomberg money to launch M in Spanish language ads in Florida Harris faces pivotal moment with Supreme Court battle MORE, over his support for the 1994 crime bill.

Speaking on CNN’s “State of the Union,” de Blasio called Biden’s work on the bill "a huge mistake."

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“That crime bill was one of the foundations of mass incarceration and a very painful era in our nation’s history,” he said. “[Biden] and anyone else has to be accountable for every vote they take and what’s on their record. And I think that was a huge mistake.”

De Blasio added that the crime bill and other federal policies "were a big part of why untold thousands of people and families had their lives entirely disrupted and in many ways destroyed."

“We’ve got to break out of that, and anyone responsible has to be accountable,” he said.

Mayor Bill de Blasio on the 1994 crime bill: “That crime bill was one of the foundations of mass incarceration … The [former] Vice President and anyone else has to be accountable for every vote they take ... I think that was a huge mistake” #CNNSOTU pic.twitter.com/APqOXjtSP7 — CNN Politics (@CNNPolitics) May 26, 2019

His comments fell in line with those from fellow 2020 contender Sen. Kamala Harris Kamala HarrisHarris faces pivotal moment with Supreme Court battle Nearly 40 Democratic senators call for climate change questions in debates Joe Biden has long forgotten North Carolina: Today's visit is too late MORE (D-Calif.), who said earlier this month that the bill contributed to mass incarceration in the country.

Biden has defended his efforts to pass the controversial bill, saying it helped him take on the National Rifle Association.

De Blasio so far has not emerged as a significant challenger for the Democratic nomination.

A recent poll showed Biden as the only Democratic presidential candidate with a clear positive favorability rating, while the same poll found de Blasio to be the candidate with the worst favorability rating, underwater by 37 points.

Hitting Biden on the crime bill gives the New York mayor a chance to tout his work on his city's criminal justice system. On Sunday he said New York had reduced the jail population by about 30 percent and is planning to close Rikers Island.

“We are ending the era of mass incarceration in New York City,” he said.

The New York City mayor dismissed his low favorability ratings, which have dogged the early days of his campaign and prompted CNN’s Dana Bash to ask if he has a “likability problem.”

De Blasio said he had overcome such polls to win two elections as New York's major.

“I found this with polls over and over again,” he said. “If I believed the polls and listened to the polls in all my other elections, I might just have stayed home.”