The crisis within India's Congress-led United People's Alliance (UPA) deepened Thursday with its second largest constituent, Trinamool Congress (TMC), lashing out at the Congress for the rail fare hike and Railway Minister Dinesh Trivedi, who is a Trinamool Congress Member of Parliament ( MP).

West Bengal chief minister and TMC chief Mamata Banerjee while addressing her party legislators here at the state Assembly alleged, "The rail fare hike is a game plan of the Congress to embarrass our party."

She was hinting that her own party minister Trivedi was in league with the Congress leadership and in fact a few weeks ago she had chided Trivdei for having met Congress general secretary Rahul Gandhi.

Till now Trivedi has neither resigned nor communicated with Mamata Banerjee and kept repeating that he would only resign if asked by the Prime Minister or his party leader Banerjee.

Banerjee instead has sent the name of her party loyalist Minister of state for port and shipping Mukul Roy to replace Trivedi as the railway minister.

Prime Minister Manmohan Singh is yet to act on Banerjee's letter and Trivedi has remained railway minister up to now, much to the ire of Banerjee.

Meanwhile, the Congress in no uncertain terms has sent a message to Banerjee that her blackmailing tactics by attending swearing in ceremonies of chief ministers of the northern states of Punjab and Uttar Pradesh, whose parties are not part of the UPA, was intolerable and the Congress would no longer succumb to her pressure.

Friday the TMC MPs will sit outside the parliament demonstrating against the UPA government protesting against the railway budget.

After Friday's union budget by finance minister Pranab Mukherjee, if the TMC found there was an imposition of a surcharge, Banerjee might use it as an excuse to pull out of the UPA.

However, the Congress is not much worried as it is negotiating with Samjavadi Party supremo Mulayam Singh Yadav whose party has 22 MPs compared with 19 PMs of TMC.

For the Congress it is just a matter of time till they rope in Mulayam Singh Yadav and offer him a ministerial berth.

The other theory, according to some political observers, is that the government agrees to either a total or a partial rollback of hike in fares, leading to a truce between the TMC and the Congress-led government.