Chicago (CBS) — Ja’Mal Green, the 23-year-old Black Lives Matter activist who set his sights on city hall blamed both Willie Wilson’s money and Chicago’s ballot access requirements for ending his campaign Monday.

“My desire to be a voice for the people was no match for Willie Wilson’s dirty dollars,” Green said.

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Wilson, the millionaire businessman, made no apologies about using his deep pockets to challenge Green’s petitions.

“This is a big boy’s game, and you’ve got to have something to come to the table with,” Wilson said. “Otherwise, you get left out.”

But, Chicago’s requirement for petition signatures is a huge hurdle in itself.

“The current signature requirement is 12,500,” election law attorney Anish Parikh said. “That is no easy task to accomplish over the course of 90 days.”

New York requires 3,750 signatures while Los Angeles and Philadelphia require only 1,000.

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“Any state in this country, you don’t need this amount of signatures and this process isn’t so gruesome,” Green said.

As recently as 1995, it took only 3,000 signatures to run for Chicago mayor. But, after Mayor Daley backed a measure to make elections non-partisan, the elections board ruled 25,000 signatures were needed.

State lawmakers later cut that to 12,500, which is still high, compared to other big cities.

“The purpose was to protect incumbents,” Green said. “The purpose was to protect the rich and powerful.”

Green said he intends to lead a campaign to increase ballot access, possibly by filing a lawsuit to reduce the number of signatures needed.

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Willie Wilson said he’s now aiming to knock two other mayoral candidates off the ballot: Dorothy Brown and La Shawn Ford.