Prime Minister Narendra Modi's Bharatiya Janata Party (BJP) is on course to win a landslide majority in Maharashtra state, India's richest, according to trends.
The BJP and its allies are in the lead with almost 220 seats out of 288, comfortably placed above the halfway point needed to form a government.
Maharashtra, which has the Indian financial hub of Mumbai as its capital, is one of the most political states in the country.
The BJP, however, expects a defeat in the eastern Indian state of Jharkhand, where the main opposition Congress and its allies are on track to win.
These were the first regional elections in Maharashtra since crucial parliamentary elections earlier this year, in which Modi returned for a historic third term but lost his majority, having to depend on regional allies to form a government .
Maharashtra is one of the states where the BJP suffered a setback and opposition parties won two-thirds of the parliamentary seats.
Modi's party currently leads the current government in Maharashtra alongside splinter factions of two regional parties, the Shiv Sena and the National Congress Party (NCP).
Political analysts say keeping the BJP in the state will provide a much-needed boost to the party, which also won regional elections in the northern state of Haryana last month.
“This result surprised us. We knew we would win but we did not expect such a crushing result,” BJP spokesperson Pravin Darekar told reporters in Mumbai.
The result will also decide the fate of regional heavyweights, many of whom switched parties overnight in both states.
In Maharashtra, Modi led his party's campaign from the front, announcing several welfare schemes, many of which were aimed at farmers. The state is a major agricultural belt and producer of crops like onion, soybean and cotton.
The opposition also made similar promises, including abolishing agricultural loans and providing financial assistance to women and the elderly.
Critics have pointed out that competing election promises would mean the new government would face a serious budgetary challenge to deliver on them, or risk facing voter anger.
The state has experienced significant political unrest in recent years. The BJP-led coalition remained in power after some lawmakers from the Shiv Sena and NCP parted ways with their parties and joined the government.
Meanwhile, Jharkhand, where seven chief ministers have ruled since the state's inception in 2000, has also witnessed political upheaval in recent months after its chief minister Hemant Soren was arrested in February on corruption charges, which he denied.
After his release in June, Soren quickly hit the road, trying to capitalize on sympathy votes.
While the BJP called Soren corrupt, it alleged that the federal government was unfairly targeting a tribal chief minister.
Tribal communities make up nearly 9% of India's population and remain one of the most marginalized groups in the country.
Like Maharashtra, Jharkhand also saw parties promising cash incentives, free electricity, jobs and health insurance.
