India's governing Congress party suffered a bruising blow Sunday, losing four keenly watched state elections in what is seen as a semifinal for the national vote next spring.

The country's main opposition, the Hindu nationalist Bharatiya Janata Party, won power in all four states, even as the brand-new Aam Aadmi Party, formed last year by anti-corruption crusaders, made an impressive debut in the capital.

Celebrations broke out at BJP offices nationwide, with party workers exchanging marigold garlands, eating sweets, setting off firecrackers and dancing to drums. At the AAP office in New Delhi, supporters in signature white caps shouted slogans and wielded brooms — their election symbol for cleaning house.