Balloting for 10 Lok Sabha seats in Madhya Pradesh and one state assembly seat began Thursday, officials said.
Of the 10 seats going to polls, eight are in the tribal-dominated Malwa-Nimad region in the western part of MP.
The Congress had won six of these eight seats in 2009, while the Bharatiya Janata Party (BJP) had bagged the remaining two in the region.
The BJP had also won Vidisha and Betul, the two seats outside Malwa-Nimad going to polls.
The fight for Vidisha is in the spotlight in the presence of high-profile candidates such as BJP's Sushma Swaraj and Lakshman Singh, brother of Congress general secretary Digvijaya Singh.
Swaraj had won here in 2009 by a margin of over four lakh votes. Former prime minister Atal Bihari Vajpayee and chief minister Shivraj Singh Chouhan have tasted victory in the past from Vidisha.
In Malwa-Nimad, the saffron party had inflicted a heavy loss on the Congress in the 2013 assembly polls. The area borders Rajasthan, Gujarat and Maharashtra on three sides and carries the imprint of cultures of the three states.
These elections are being viewed as the Congress' battle for survival in Malwa-Nimad.
State Congress president Arun Yadav and party's tribal face Kantilal Bhuria are contesting from Khandwa and Ratlam, respectively.
Among other prominent candidates in the fray are Mandsaur parliamentarian Meenakshi Natarajan, considered close to Congress vice-president Rahul Gandhi, and Sumitra Mahajan, a seven-time BJP MP from Indore.
More than 16 million voters are eligible to exercise their franchise in the last phase, which has 118 candidates in the fray.
Of the state's 29 Lok Sabha constituencies, voting for 19 seats was held in two phases on April 10 and April 17.
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Key candidates in fray
With Agency inputs
Here's a map for the constituencies going to polls on Thursday. On searching, you will get details of all parties fighting from a constituency and key candiates there: