POLITICIANS have vowed to collect evidence to prove Bridport's one-hour free parking benefits trade in the town.
The move comes as the number of signatures on the petition opposing Dorset County Council's plans to charge for on-street parking tops 5,000.
Traders and politicians met MP Oliver Letwin to discuss the charges.
Mr Letwin said: "I think the traders, the chamber of commerce and the town council have made an overwhelmingly strong case that Bridport and on-street parking charges don't mix.
"I shall try to persuade the county council that they should not introduce on-street parking charges in the town, and should seek other means of balancing the books of the parking enforcement account."
Market traders' spokesman Ron Gregory, who started the petition, said they were still collecting signatures but it was time for politicians to take the fight on.
Town, district and county councillor Ros Kayes said they would be doing just that.
She said: "We are organising a survey like we did with the hospital to find out how people who park in the town are using the roadside parking.
"We want to provide the county council with evidence that this will be very damaging to our town centre.
"Quite often they are people from the villages who don't have a shop in the village who come in several times a week and a lot of them are elderly.
"If they can't park in Bridport for free they will go and park in supermarket car parks.
"We have to have proof to make a special case for Bridport."
She said the petition and information would be presented to the environment overview committee on October 1.
At a town council meeting, former town crier John Morey wanted councillors to demand an explanation about how parking meters could reduce congestion.
He said: "Which planet is this man from or he wouldn't come up with a suggestion like this which is going to ruin the town."
John Nester of Bridget's Market said he hadn't heard of a single person who was not opposed to the idea.
He said: "It is completely ludicrous."
Matthew Piles, traffic manager for Dorset County Council, said the proposals were essential to ease congestion and keep traffic moving safely and efficiently.
He said: "The greater turn-over of visitors, who can park cheaply for short periods while they do their shopping, will also benefit traders and the local economy.
"It is not about raising revenue. Any money raised from on-street parking would be reinvested into the council's traffic management service. It would fund the maintenance of signs, lines and meters, plus enforcement work.
"Nothing has been agreed at this stage," he said.