The de-escalation of the fighting suggests negotiations are ongoing between the armed forces and rebels
More than 155 million people are eligible to vote in the second phase, which covers 95 parliament constituencies in 12 states including parts of restive Jammu and Kashmir. India's parliament has 545 members.
"If the non-BJP parties perform well in these two states, then they would still be having a chance of forming a non-BJP government at the centre," said Sanjay Kumar, director of the Centre for the Study of Developing Societies, a think tank based in the capital, New Delhi.
Votes will be counted on May 23 and the results are expected the same day.
The BJP began the election as the frontrunner, with Modi setting muscular national security as his campaign plank after a renewal of hostilities with neighbouring Pakistan.