The suit filed Tuesday claims T. Milton Street Sr. provided more than 1,500 invalid signatures on his nominating petitions and doesn't meet the residency requirements to run in May's Democratic primary.
According to the suit, fewer than 750 of the 2,408 signatures on Street's nomination papers are valid.
The suit also says Street hasn't lived in the city long enough to run. He was released from a federal prison in Kentucky last year after serving a tax-evasion sentence.
Street says he's a viable candidate and will fight the challenge. He is the brother of former Mayor John Street.
Nutter's political-action committee is paying the suit's costs.
