Some analysts believe the BJP's share within the ruling alliance may fall, making it more vulnerable to the demands of smaller partners.

North

The BJP and allies look set to sweep the board in Haryana and Himachal Pradesh. They are also heading for big leads in Madhya Pradesh, Rajasthan and Bihar.

Congress had hoped to build on good results in last year's state assembly elections in Madhya Pradesh and Rajasthan, but fell back in both.

In Rajasthan, it won only nine of the 25 seats, the rest going to the BJP. Local Congress leader Balram Jakhad was among the losers.

Editor of Outlook magazine Vinod Mehta and sociologist Dipankar Gupta assess voting patterns

The outcome was less happy for the BJP alliance in Punjab and Uttar Pradesh.

In Punjab, two senior Akali members, Surjeet Singh Barnala and Sukhbirsingh Badal both lost and Congress looks set to take many of the 13 seats.

In Uttar Pradesh, early indications suggest that the BJP and its allies may win no more than 30 seats compared with 59 at the last election. Almost all the opposition parties, including Congress, appear to have gained.

Dipankur Gupta looks at why Congress lost out in UP

In the troubled region of Jammu and Kashmir, the National Conference has won the seats of Srinagar and Baramullah in the Kashmir valley. Omer Abdullah - the son of chief minister, Farooq Abdullah - won in Srinagar.

Among the losers was former National Conference leader, Saifuddin Soz.

Mr Soz had voted against the government during last April's confidence vote, in defiance of his party's official position. In Jammu, the BJP is reported to have a winning lead in two seats.

South

In Andhra Pradesh - where the BJP joined forces with the state's governing Telegu Desam Party (or TDP) - the alliance is leading in 30 of the 42 parliamentary seats.

Analysts believe the BJP would not have performed half as well without the TDP's support.

In Tamil Nadu, the BJP also holds an early lead - ahead in 20 of a total of 39 seats along with its ally - the Dravida Munnetra Kazhagam.

In Karnataka, Congress won a comfortable majority. It took 18 of the 28 parliamentary seats and an overall majority of the state assembly.

Congress President, Sonia Gandhi, led the way, winning in Bellary by a margin of 50,000. It is thought Congress benefited from the split in the state's governing Janata Dal party.

In Kerala, the Congress-led alliance, the United Democratic Front, is also doing well. It has won two seats and is leading in a majority of the other parliamentary seats.

East

In Bihar, the BJP and its allies look set to win the majority of seats.

Laloo Prasad Yadav: Lok Sabha seat in doubt

The state's colourful former chief minister, Laloo Prasad Yadav, is thought to be in danger of losing his own Madhepura seat. The declaration is being delayed by an investigation into alleged vote-collection fraud. Mr Yadav's Rashtriya Janata Dal party has won two other seats.

In Orissa, the BJP and its regional ally, the Biju Janata Dal, have established a comfortable lead. The two parties look set to win at least 19 seats. Congress is expected to lose three of the five seats it won at the last election.

In West Bengal, the BJP has won only two seats. Its allies, the Trinamool Congress, has won five and is ahead in another four.

The governing Left Front has so far won 11 seats and is leading in another eight.

In Assam, Congress is expected to gain most of the 14 seats. It also looks to be in front in Arunachal. In Tripura, the Left Front has won both seats.

In Meghalaya, Congress and its breakaway faction, the Nationalist Congress Party, have got one seat each. The NCP leader and former Lok Sabha speaker, Purno Sangma, won by a big margin.

West

The BJP-led alliance also performed well in the economic powerhouse states of Maharashtra and Gujarat.

The BJP-Shiv Sena alliance dominated Congress and the Nationalist Congress Party in the three-way contest for Maharashtra.