India's ruling party looked set to lose power in at least one of three traditional stronghold states releasing election results on Tuesday, in a blow to Prime Minister Narendra Modi ahead of national polls in 2019.

Early election results in the central state of Chhattisgarh indicated the main opposition Congress party of Rahul Gandhi would win 59 seats compared to just 11 for Modi's Bharatiya Janata Party.

The Hindu nationalist BJP has ruled Chhattisgarh for the past 15 years.

Read: Modi defeats no trust vote, Rahul wins confidence

The race looked closer in Rajasthan and Madhya Pradesh, two other traditional strongholds of Modi's BJP that were also counting votes following elections in the states this month and last.

In central Madhya Pradesh, home to 73 million people, early results put the BJP neck-and-neck with Congress, as observers said it was too early to call the result either way.

Similarly in the western desert state of Rajasthan — ruled by the BJP's Vasundhara Raje, a maharani or princess — Modi's party was predicted to win 74 seats compared to 97 for Congress.

Television footage showed Congress workers bursting firecrackers and dancing at regional party offices in both states.

Tuesday's results are being seen as a referendum on 68-year-old Modi, who will be seeking a second term in the office in national elections due by May 2019.

Defeats in Chhattisgarh, Madhya Pradesh and Rajasthan would dent his invincible image and put the party on the back foot.

It would also strengthen 48-year-old Gandhi — scion of the Gandhi-Nehru dynasty — with Congress having lost more than a dozen states to the BJP since Modi became prime minister in 2014.

The BJP currently rules 19 out of 29 Indian states either outright or in alliance with local parties. Congress rules just two states, including one in alliance with a regional partner.

Political commentators have linked the BJP's apparent dwindling support to growing rural distress and unemployment rates in the country.

Nearly 55 percent of India's 1.25 billion population is directly or indirectly dependent on agriculture, and farmers form an important voting bloc for parties.

In two other states also releasing results on Tuesday, Telangana in the south and remote Mizoram in the northeast, regional parties looked to be leading.

Gandhi's Congress is leading efforts to stitch a larger alliance of regional parties to take on the BJP next year, convening a meeting to this effect on Monday in Delhi.