An upstart anti-corruption party is heading for an overwhelming victory in elections to install a state government in India's capital, a potentially huge blow for Prime Minister Narendra Modi's Hindu nationalist party.

The trends released by India's Election Commission show that the Aam Admi Party, led by Arvind Kejriwal, is leading in 56 of the 70 seats while Modi's Bharatiya Janata Party is ahead in eight seats. More than one-third of the vote has been counted so far.

If the trend holds, it would be a major disappointment for Modi and his party, which has been on a winning streak since sweeping national elections in May.