Hip-hop magnate Russell Simmons, joined by a group that wants to outlaw horse-drawn carriages in New York City, demonstrated growing impatience Thursday with Mayor Bill de Blasio's failure to fulfill his campaign promise of a ban.

The effort is stuck in the City Council, some of whose members have recoiled at aggressive tactics by horse-carriage foes. There was new friction after Simmons, in a winding soliloquy, compared what he calls animal abuse to slavery and the Holocaust.

"There were people for slavery. . . . There were people who put people in ovens," Simmons said when asked about council members supportive of the carriage industry.

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Councilman David Greenfield (D-Brooklyn) in an interview called it "outrageous" to compare the plight of horses with the "worst genocide in modern history."

Greenfield, undecided on the ban, added in a statement that Simmons "doesn't help his cause when he engages in outrageous hyperbole that minimizes the murder of much of my grandparents' family."

Simmons, who rode to City Hall in the prototype electric buggy that has been pitched as an alternative to carry tourists around Central Park, also took swipes at de Blasio. "He's not as skillful a politician as we had hoped," Simmons said.

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De Blasio had vowed as a candidate in 2013 and upon taking office to immediately shut down the "inhumane" carriage horse business, pleasing animal-rights groups who ran attack ads against a Democratic primary opponent, Christine Quinn. But in the year and half since he took office, there has been no resolution.

A council bill to offer the 300 carriage drivers alternate employment behind the wheel of green taxis awaits environmental review, committee hearings and votes to pass the measure.

Representatives of the animal rights group NYCLASS who invited Simmons to try out their "horseless carriage" stood around him with signs that read, "18 months & waiting, Mayor de Blasio."

Asked about the delay, de Blasio said Thursday it is "just part of the reality of leadership" and he is still committed to the effort.

"It's well-known there are different views on the City Council," de Blasio told reporters in the Bronx. "It's something that I'll keep working on until we get the work done." As for Simmons' criticism, he said, "I'm not worried about it."

The NYCLASS lobbying blitz backfired in at least one case when Councilwoman Debi Rose (D-Staten Island) sided with the drivers. She sarcastically thanked them for a barrage of tweets, Facebook messages, emails, mailers and phone calls, saying, "They certainly helped me to make up my mind."

Simmons, a music producer, clothing designer and reality TV star who is also an activist, said he expected de Blasio to be more skilled at deal-making and persuading council members to his side.

He called the mayor "weak" and "compromised" on that issue as well as another cause Simmons has championed, curbing police abuses.With Matthew Chayes