next Image 1 of 2

prev Image 2 of 2

Indians are voting in the fourth phase of a staggered national election, with Prime Minister Narendra Modi's party facing a major test.

Voting is being held in nine states on Monday. The remaining three phases will be completed by May 19. Vote counting begins May 23.

Monday's polling is a big test for Modi's Bharatiya Janata Party and its allies, who won 56 of the 72 seats being contested Monday in 2014 elections that swept the BJP to power.

But it suffered a setback in December when the opposition Congress party wrested power from the BJP in three key state elections — Rajasthan, Madhya Pradesh and Chhattisgarh. Rajasthan and Madhya Pradesh vote on Monday.