Trinamool Congress supremo Mamata Banerjee, set to take over as West Bengal Chief Minister on Friday, resigned as railway minister on Thursday.
Railway sources said Banerjee sent her resignation to Prime Minister Manmohan Singh.
Banerjee took over as Railway Minister of UPA-II government in May, 2009. She had also held the ministry for less than two years in the NDA government.
Trinanool Congress General Secretary Mukul Roy, currently Minister of State for Shipping, is being seen as the front-runner for taking over the Railway Ministry.
Banerjee, who engineered the landslide victory of the Trinamool Congress-Congress combine, will be sworn in as West Bengal's first woman Chief Minister on Friday.