Senior Congress leader and Revenue Minister Narayan Rane will not abide by his party's directives.
Rane said he will lead the agitation against the Konkan Railway on July 9 if the Railway Ministry does not meet his demands by Thursday.
Rane wants a train from Mumbai to Sawantwadi. His other demands include jobs for the locals, who have given their land for the Konkan Railway project and a railway terminus at Sawantwadi.
He also wants all major trains to stop at prominent stations in Konkan.
Chief Minister Ashok Chavan had asked Rane to withdraw the protest when he announced it three weeks ago.
Giving Chavan a royal snub on Wednesday, Rane reiterated his plan. He asked Banerjee to take decision within a day. "If the minister fails [to take a decision] by tomorrow, we will agitate," Rane said.
His son Nilesh, a Member of Parliament, will also join the protest.
Chavan had said he would meet Railway Minister Mamata Banerjee to resolve the issue. "I would request Congress leaders to withdraw the protest," he had said last week.
Rane has another political reason to defy the Congress.
A day after he had announced his plan, his old party the Shiv Sena declared its protest on June 30. The saffron party withdrew the protest after seeking an assurance from Banerjee.
Rane, who was a force in Konkan in his Sena days, is also desperate to re-establish his hold over the region.
The Congress could not bag the number of Assembly seats it had expected given Rane's clout in the belt and this is Rane's chance to salvage his reputation in the party.
His men in Konkan have started preparing for the agitation. Rane is expected to lead the agitation at Kankavli while Nilesh will take care of protests in Ratnagiri.