More than half of the 95 seats voting in the second round of Lok Sabha elections today are in Southern India, representing nearly nine crore voters. People in 38 constituencies of Tamil Nadu, 14 of the 28 in Karnataka and the lone seat in Puducherry began queuing up early on Thursday in the second phase of the mammoth, seven-round general election in which opposition parties are trying to stop Prime Minister Narendra Modi from winning a second term. The main opposition Congress party and its allies need to win big in the southern states if they hope to oust the BJP.

Here is the 5-point guide to what is at stake in this key battle:

1. Karnataka is mostly a two-sided contest between the BJP and the ruling Congress-Janata Dal-Secular (JDS) coalition. Congress leader Siddaramaiah and JDS supremo HD Deve Gowda, who have shared a rocky equation for over 15 years, campaigned together this time in their attempt to pitch a united front against the BJP.

2. The ruling alliance is grappling with resentment among its workers over the seat-sharing agreement that has eaten into the two parties' share of constituencies. An adverse result could impact the longevity of the coalition government in the state.

3. It is much more complex in Tamil Nadu which has a four-cornered contest. The ruling AIADMK-led alliance including the BJP and a host of smaller state parties are up against a coalition led by its longtime rival DMK that includes the Congress and the Left. The AIADMK spin-off TTV Dhinakaran's AMMK or Amma Makkal Munnetra Kazhagam and actor-turned-politician Kamal Hassan's MNM or Makkal Needhi Mariam are the two other parties.

4. Tamil Nadu is also holding by-elections for 18 assembly constituencies most of which the ruling AIADMK must win in order to stay in power. It is also the first election in several decades when the two main parties don't have their iconic leaders J Jayalalithaa, who died in 2016 and M Karunanidhi, who died in 2018.

5. The elections in Tamil Nadu are once again mired in allegations of voters being bribed. The election in the Vellore Lok Sabha constituency was canceled after a huge haul of cash.