Former Defense Minister V.P. Singh scored a convincing victory Saturday in off-year parliamentary elections, setting up a possible national challenge to Prime Minister Rajiv Gandhi.

Gandhi's Congress Party won only two seats in Thursday's voting, according to results announced Saturday. It had held all seven seats that were contested in the elections.Singh and two other opposition candidates won seats in the Parliament's lower house, while a fourth opposition candidate was leading by more than 27,000 votes in the Udhampur district in the northern state of Kashmir.

Vote counting was delayed in the seventh district, in Haryana state, after Congress Party officials accused the opposition of massive vote-rigging.

Gandhi appeared undismayed by the weak showing of his Congress Party.

"In any by-election, the ruling party gets it in the neck," Gandhi told reporters in south India. "The Congress is satisfied over the outcome of the polls as it has come at a difficult time."