With new stipulations on the minimum capacity for rugby grounds in elite competition, the club want to expand Franklin's Gardens and need the money from the potential sale of the car park in Edgar Mobbs Way to Asda.
But after talks on Tuesday night with council chiefs, Saints chairman Keith Barwell said he was satisfied that they don't want a large retail development in the borough to be based outside the town centre, effectively blocking any deal.
Mr Barwell said: "We had a heavy beating from the council on this and they said they don't want anything that takes trade away from the town centre.
"They say they speak with one voice on this and they will not be deterred from their aim under any circumstances.
"But the problem is they can't stop this trend. What are they going to try to do next? Stop internet shopping because that detracts from the town centre?
"And is it realistic that in 2026, or probably longer, the new Grosvenor Centre, built by Legal and General, is going to suddenly emerge like a beautiful butterfly? In the meantime we would be having two lost decades.
"That's why I want to start a debate about what the people of Northampton want.
"Is this town being run by the council or Legal and General?"
The club believes it will be supported by the majority of its fans, local business, who may benefit from increased support, and its corporate sponsors.
It also argues that the ability to play big European games at Franklin's Gardens would see the town share in reflected prestige.
Although Northampton Borough Council could not say yes or no to the plan their backing carries significant weight with planning authority the West Northamptonshire Development Corporation.
Mr Barwell pointed to what he says are discrepancies in the borough council's unofficial policy of town centre-only retail development with regard to an undetermined application for an Aldi store in Wellingborough Road, Northampton, which the local authority's officers have backed
He said: "Why is it recommending this new store which is even nearer to the town than our car park? I presume that would also detract from the town centre.
"I wonder if anyone can see the difference between this Asda store and Aldi.
"There's a saying that if there's no wind, row. It would be nice if the council put a bit of wind behind us instead of providing an obstacle.
"We are now going to take a very a highly aggressive profile.
"The council asked me not to but I'm going to take a lesson from my print union days.
"Their method of negotiation was to come in, kick you between the legs as hard as possible then sit down to talk. I regret having to take that line but we have asked nicely."
A Northampton Borough Council spokeswoman said that councillors on its planning committee had since expressed "serious concerns" about the planned Aldi store and insisted the local authority wanted to help the rugby club.
She said: "Northampton Saints are a great asset to the town and the borough council is fully supportive of the club's aspirations to make Franklin's Gardens an even more impressive ground.
"We know and appreciate that an increase in the size of the ground would enable the Saints to remain one of the best supported rugby teams in the country.
"We have met with the Saints to discuss their aspirations and how Northampton Borough Council could work to assist them. We intend to continue these discussions on a positive basis and hope to meet the Saints again before Christmas.
"Any planning applications will be considered on their merits and key consideration will be the impact of development on the town centre. The borough council believes the future of Northampton requires a strong and high performing town centre."