Lhota, a former deputy mayor to Rudolph Giuliani who is trailing badly in the polls, centers the ad around the dramatic video of the biker attack that left several people, including a young father, injured. It then segues into harrowing black-and-white images from the 1970s and '80s, including footage of an overturned police car, a man holding a gun and corpses sprawled on the ground.
The 30-second spot, which will air on the city's broadcast networks, warns that de Blasio has a "recklessly dangerous agenda on crime" because the public advocate suggested that he would meet with biker groups.
The ad, by far the most negative in an increasingly nasty campaign, comes on the heels of Lhota's accusations during a Tuesday night debate that de Blasio is "untested" and unable to continue the city's historic reduction in crime that began in the 1990s under Giuliani. Lhota has frequently criticized de Blasio for wanting to reform the police department's stop-and-frisk policy, which allows officers to stop anyone deemed acting suspiciously.
De Blasio condemned the ad, calling it desperate and inappropriate.
Speaking to reporters at a rally in Manhattan, de Blasio compared it to the infamous "Willie Horton" commercial run by George H.W. Bush's 1988 presidential campaign against Michael Dukakis. The ad featured Horton, an African-American who committed violence while out on furlough, to paint Dukakis as soft on crime. Critics called it race-baiting.
"This is just like the Willie Horton ad," de Blasio said. "It is divisive and negative."
A Lhota spokeswoman said the campaign stands by the ad.
The ad's aggressive tone was the same tenor Lhota planned to use Tuesday night in the first of the candidates' three debates, but he was frequently put on the defensive by de Blasio.
The Democrat, up nearly 50 points in some polls, surprised observers who expected him to stick with his recent strategy, one typical of front runners, of staying above the fray and avoiding gaffes. Instead, he attacked Lhota and prevented the Republican from delivering the blows his struggling campaign desperately needed.
The election to replace outgoing Mayor Michael Bloomberg is Nov. 5.
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