PM Modi focused his campaign on Uttar Pradesh, West Bengal and Odisha

As campaigning for the seventh and the last phase of the national election comes to an end, we try to decode the science behind Prime Minister Narendra Modi and Congress chief Rahul Gandhi's campaigns - why they chose which seats, which state was top priority and what was the rationale behind it.

PM Modi addressed a total of 144 rallies and roadshows this election campaign season.

Uttar Pradesh, a state that gave the BJP-led National Democratic Alliance or NDA 73 off 80 seats in the last Lok Sabha elections, was the PM's top focus. He held 36 rallies and roadshows here, which is an average of one rally per 2.3 seats.

The prime minister's other big focus was West Bengal - a state where a bitter battle was fought between his BJP and Mamata Banerjee's Trinamool Congress. The BJP currently holds two seats in Bengal and is hoping to make massive dents in the Trinamool armour. PM Modi held 17 rallies for the state's 42 seats, averaging about one per 2.5 seats.

The next state on PM Modi's priority list was Odisha, another state where the BJP is trying to make inroads. The BJP only holds one out of the state's 21 seats. The other 20 are held by Naveen Patnaik's Biju Janata Dal. PM Modi held eight rallies in Odisha, which is one rally per 2.6 seats.

40 per cent of PM Modi's campaigning was in UP, Bengal and Odisha alone - 58 of 144 rallies. These three states make up for 143 Lok Sabha seats - which are extremely crucial for the BJP.

Sources have told NDTV that the BJP's strategy is extremely clear - to make gains in West Bengal and Odisha and make up for any losses in the north.

Rahul Gandhi addressed 18 rallies in Uttar Pradesh

In contrast, Rahul Gandhi addressed 125 rallies this election. His four priority states were Uttar Pradsh, Rajasthan, Madhya Pradesh and Kerala.

In UP, Mr Gandhi addressed 18 rallies for 80 seats which is an average one rally for every 4.5 seats. Uttar Pradesh, particularly eastern UP, is a prestige battle not just for Rahul Gandhi but also his sister Priyanka Gandhi who made her formal debut in politics earlier this year and is the party's general secretary in charge of eastern Uttar Pradesh. In the 2014 election, the Congress had won just two seats in the state - Rahul Gandhi from Amethi and his mother Sonia Gandhi from Raebareli - both Congress strongholds.

The Congress's fortunes have been dwindling in Uttar Pradesh Lok Sabha and Vidhan Sabha polls since 1989, despite the fact that Sonia Gandhi and Rahul Gandhi have been winning elections from this very state.

In Rajasthan, a state where the Congress defeated the BJP in state polls late last year, Rahul Gandhi held 12 rallies for 25 seats - an average of one rally per 2.08 seats. The Congress has just one seat in Rajasthan, while the rest are with the BJP.

Rahul Gandhi's biggest surprise this election has been his journey down south, which possibly explains him contesting from Wayanad in Kerala in addition to his constituency Amethi. In Kerala, Rahul Gandhi addressed 12 rallies for the state's 20 seats, which is an average of one per 1.66 seats. The party has seven seats in Kerala. The Congress hopes Kerala could deliver and make up for the losses elsewhere.

The Congress president held 52 of his 125 rallies in Uttar Pradesh, Rajasthan, Kerala and Madhya Pradesh. Apart from Rajasthan, the Congress is banking heavily on Madhya Pradesh - another state that went to the Congress in December 2018 state elections. A total of 10 rallies were held by Rahul Gandhi in Madhya Pradesh.

The seventh phase of polling will take place tomorrow; results for the national election will be counted on May 23.