A Boston City Hall attorney who was suspended after he put in a bid to run for mayor last spring has filed a lawsuit, alleging that Mayor Michelle Wu and her staff stymied his candidacy and retaliated by placing him on paid administrative leave, according to a copy of the federal complaint.

John F. Houton lives in the South End and worked in the city’s Law Department for 18 years, including the past 14 years as in-house counsel for the city’s Treasury Department. He was one of 13 candidates who filed paperwork with the city in May to challenge Wu.

At the time, Houton told the Globe he believed the decision to put him on leave was a retaliatory response to his mayoral campaign.

The consequences of Wu’s actions have been dire, according to Houton’s 74-page complaint filed earlier this m

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