As Uttar Pradesh goes into the third phase of Assembly polls on Wednesday, covering 57 constituencies, it could be a make-or-break case for Chief Minister Mulayam Singh Yadav's bid to retain power.

The reasons for that are three: a sizeable presence of Muslim voters, rumblings of discontent in ruling Samajwadi Party in some constituencies and mounting challenge from political rivals.

The 57 seats going to the polls in the third phase are spread across ten districts, several of whom are Muslim dominated.

In the last Assembly elections in 2002, the Muslims, who hold the key to the success of candidates in 30 to 35 seats, had by and large supported the SP, which bagged 25 seats.

However, this time, the party is likely to find it tough to retain the number.

The SP is again banking heavily on its Muslim-Yadav vote bank in the face of determined bid by Congress president Sonia Gandhi and her son Rahul to woo the Muslims in the districts in the last couple of days.

The polling in the phase would also decide the fate of Yadav, who is contesting from Gunnaur in Budaon district, and several of his cabinet colleagues, including the firebrand minister for Parliamentary Affairs Azam Khan in Rampur.

Given the sizeable presence of Muslims, all parties have tried to woo the voters of the community.

Prime Minister Manmohan Singh, addressing a rally in Afzalgarh on Sunday, had promised to implement Sachar committee recommendations for welfare of Muslims and offered to pay for learning of Urdu.

The SP is facing revolt in some key constituencies, which could adversely affect its prospects in Moradabad and Shahjahanpur districts.

SP Lok Sabha member from Moradabad Shafikur Rehman Burq has turned a rebel and has fielded his son Mumlukur Rehman as a Rashtriya Lok Dal candidate from Bahjoi seat against SP's official nominee Iqbal Mehmood.

For Burq, the seat has become a prestige issue. He said he would not campaign for SP candidates anywhere in the area.

Besides, the ruling party is also facing revolt at Jalalabad seat in Shahjahanpur district where its sitting MLA has joined Congress and is in the fray as its candidate.

A similar tussle is being witnessed at Swar Tanda seat in Rampur district, where Azam Khan has refused to campaign for SP nominee Kazim Ali Khan who is the son of senior Congress leader Begum Noor Bano.

Khan's antipathy towards the Begum is well-known and he was not present even at the SP chief's election rally at Swar Tanda.

Besides, electoral fortunes of UPCC president Salman Khursheed's wife Louis Khursheed, who is contesting from Kaimganj, and controversial Rashtriya Parivartan Dal President D.P.Yadav, father of the Nitish Katara case accused Vikas Yadav, who is in the fray from Sahaswan, would also be decided in the polling.

The importance of the third phase of polling could be measured by the fact that Congress chose to field the prime minister in the electioneering in UP for the first time during this time.

Congress president Sonia Gandhi addressed a series of meetings at Bijnore, Rampur, Amroha and Thakurdwara while Rahul held roadshows in several assembly constituencies.

Rahul also paid obeisance at the famous dargah of Ala Hazrat at Bareilly.

Congress had won four seats -- Swar Tanda, Moradabad Dehat, Kaimganj and Tilhar -- last time but hopes to increase its tally further banking on the support of Muslims.

The BJP, which had 11 seats in the outgoing Assembly from the constituencies going to poll in this phase, also hopes to reap rich dividends by what it claims a split in Muslim votes at several places.

Apparently encouraged by civic bodies election results, the saffron party expects to win a majority of seats in urban areas.

BSP supremo Mayawati also addressed a series of election rallies in the areas going to the polls in the third phase and is banking on Dalit-Muslim-Brahmin combination to capture the SP strongholds.

The BSP has fielded 23 Muslim candidates this time.