The first day of voting in India's post populous state - Uttar Pradesh - ended peacefully with about 63 percent of the the state's 26 million eligible voters casting a ballot, according to the election commisssion.

The election is widely viewed as a mid-term test for Prime Minister Narendra Modi and his Bharatiya Janata Party (BJP).

Some 140 million people in Uttar Pradesh will cast ballots in seven stages over the next month to elect a new state assembly, currently headed by Chief Minister Akhilesh Yadav and his Samajwadi Party. 

The regional party has formed a political alliance with the country's main opposition Congress Party, led by Rahul Gandhi of the Nehru-Gandhi dynasty, which was crushed in the state by Modi's Hindu nationalist party in the 2014 general election.

That vote saw the BJP win 42 percent of the vote and pick up 71 of the state's 80 seats, helping the Hindu nationalist party secure a strong nationwide mandate in the  543-member lower house of parliament.

The results of the Uttar Pradesh vote will come out on March 11, and polls show a close race between the Samajwadi Party and Congress in a first-past-the-post voting system. The Bahujan Samaj Party, a party supported by lower castes and led by Mayawati, who goes by one name, is polling in third place. Under the voting system, any party getting more than 30 percent of the vote is likely to win the state.

Halfway into Modi's term, the vote in Uttar Pradesh is viewed as a referendum on the prime minister's policies and a bellwether ahead of 2019 general elections.

Voters will be evaluating Modi's controversial ban on large bank notes, a policy designed to fight tax evasion by the rich that has also impacted the poor. Other issues include jobs, services and development in the poverty-stricken state.

A Samajwadi-Congress victory would be a major blow to Modi and likely shape political alliances against the BJP going forward.  Congress has performed poorly in state elections since it was handed its lowest-ever support in parliamentary polls, leading it to join alliances with other parties like the Samajwadi Party in Uttar Pradesh.

"If BJP loses, it would be its second major defeat since the 2015 election in Bihar state, which will prove that forming smart alignments with regional parties to beat the BJP works. This could be a template at the national level," Sanjay Kumar, director of the Delhi-based Centre for the Study of Developing Societies, told DPA news agency.

On the other hand, if the BJP won again, this might show that its national momentum would be difficult to stop, he added.

Modi has personally led the campaigning for his party, but the BJP hasn't fielded a local candidate for chief minister in Uttar Pradesh. Observers say this opens up the BJP to a defeat similar to that in Bihar in 2015.

Alongside Uttar Pradesh, multiweek elections are being held in Punjab, Goa, Uttarakhand and Manipur states. The results are due out on March 11.

cw/tj (AFP, dpa, Reuters)