The judicial review over the Gravesend Heritage Quarter has been criticised for risking the multi-million pound redevelopment at the "eleventh hour".
Councillor Tanmanjeet Dhesi, cabinet member for business at Gravesham Council, lambasted Gravesham MP Adam Holloway as "irresponsible" for supporting Urban Gravesham's challenge.
The campaign group took the council to the High Court over the £120 million scheme earlier this month which could delay the planned revamp of the Heritage Quarter by around six months.
Coun Dhesi said: "I was amazed to hear the comments made by Mr Holloway who, by supporting this legal action, will put this major regeneration of Gravesend town centre in jeopardy.
"At a time when we are trying to attract new businesses into the town and ensuring the future of existing businesses, not to mention the creation of hundreds of new jobs, this eleventh hour legal action, supported by Mr Holloway, is totally irresponsible.
"The brutal fact is that the parts of the scheme that Mr Holloway would like to see omitted or changed would make the development financially unviable."
Mr Holloway told News Shopper earlier this month: "It is a hideous, low quality development from a time when the town had low aspirations and it's completely out of date what with Ebbsfleet Garden City and Paramount Park coming.
"It's a shocker and thank God for Urban Gravesham for going in where the political class in this borough has failed miserably to do so."