Vann is challenging Republican incumbent John Testa in District 1 and is also running on the Democratic ticket.
The Westchester County Board of Elections determined that 60 percent of the entries on her petitions came from people who don't live in the district.
“I was really hoping for an election where my opponent wouldn’t attempt some sort of scheme to cheat during the petition process,” Testa said.
Vann blamed the snafu on a former campaign manager, who got signatures from people in District 4 instead of District 1.
"I remain endorsed by the Working Families Party," Vann said. "My campaign manager didn't properly check the petitions, so now I have a new campaign manager. I will run on the issues."
District 1 covers Peekskill, Cortlandt, and Yorktown.
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