New Delhi: The Congress got a boost for its prospects in Uttar Pradesh with Ajit Singh's Rashtriya Lok Dal (RLD) joining hands with it for the crucial assembly elections and also adding to strength of the party-led government at the centre by decding to join the United Progressive Alliance (UPA).

Ajit Singh met Congress president Sonia Gandhi Saturday as the two parties finally reached an accord for the assembly polls in Uttar Pradesh, expected in the first half of next year. The two parties had protracted negotiations over the seat and inclusion of Ajit Singh in the union cabinet.

Congress general secretary Janaradan Dwivedi announced the alliance after Ajit Singh's meeting with Gandhi, who is also UPA chairperson.

He said Ajit Singh had expressed his desire to join UPA. "He is expected to write a letter today (Saturday) (to Gandhi) which formalities will be completed," Dwivedi said.

Ajit Singh is expected to meet Prime Minister Manmohan Singh soon amid possibility that he would made a union minister.

Congress leader Mohan Prakash indicated that Singh could joint the cabinet, saying that like other partners in UPA, RLD will also get its share in power.

Prakash hailed RLD joining the UPA and fighting Uttar Pradesh assembly elections with Congress as a "game changer."

He also indicated that former union minister Rashid Masood and some other senior leaders would join Congress soon.

Sources said RLD is expected to contest around 50 seats of the state's total 403 seats as part of alliance.

RLD is the first party to join UPA after the 2009 general election and is expected to increase comfort level to the UPA government in the face of some of the other allies taking positions contrasting from Congress on some policy initiatives.

The alliance is also expected to improve Congress prospects in western Uttar Pradesh - the area of maximum influence of RLD. Congress' efforts to emerge as a strong alternative to Bahujan Samaj Party (BSP) in Uttar Pradesh are being spearheaded by party general secretary Rahul Gandhi.

Ajit Singh, whose RLD has five members in the Lok Sabha, had fought the last Lok Sabha polls in alliance with the Bharatiya Janata Party (BJP).

There has been speculation that Singh will given portfolio of civil aviation.