Shortly after Congress leaders met at the residence of Prime Minister Manmohan Singh late on Wednesday to discuss Trinamool Congress chief Mamata Banerjee's opposition to a Railway fare hike, and her demand to replace her nominee and Railway Minister Dinesh Trivedi with party colleague Mukul Roy, a TV channel quoted an inside source saying Trivedi has already sent in his resignation.
Trivedi, who presented his first ever rail budget, had earlier said he was prepared to quit if Banerjee asks him to do so.
"Tomorrow if my leader asks, I will resign," he said.
With Banerjee's party making it clear that a passenger fare hike was unacceptable to 'Didi', Congress leaders deliberated on possible options before the United Progressive Alliance government to pass the rail budget presented earlier in the day.
A Congress leader, on the condition of anonymity, said Banerjee has been assured that her wish on the choice of railway minister would be honoured.
Party sources also said the meeting at prime minister's residence also discussed the government's preparations for the general budget.
They said the party was exploring the possibility of mustering numbers from other parties if the Trinamool Congress decides to withdraw support.
The Samajwadi Party, which supports the government from outside, could be an option to replace Trinamool Congress, they said.
In a sign of strain in its ties with the Congress, the Trinamool Congress also moved an amendment to the motion of thanks in the president's address to parliament over the issue of the National Counter Terrorism Centre.
The Congress is also facing pressure from its ally the DMK to vote against Sri Lanka on a US-sponsored motion in the United Nation Human Rights Council (UNHRC).
Official sources said Trinamool Congress MPs had sought an appointment with the prime minister on Wednesday but the meeting did not take place. They said the meeting was likely to take place on Thursday.
Trivedi, who was picked by Banerjee to replace her as railway minister, had told the media earlier that he had not consulted his leader while proposing the hike in passenger fares.
Trivedi maintains he has done what was best for the country.
"I am in politics for duty to my country...I don't care about a job," Trivedi said.