Former Argentinian president Nestor Kirchner has stepped down as chairman of the ruling Peronist party after it suffered a major defeat in Sunday's parliamentary elections.

The coalition led by the current president, Nestor Kirchner's wife Christina Fernández de Kirchner, has lost its majority in both the Senate and the Chamber of Deputies. The main winner in the elections was an alliance of dissident Peronists, who want to introduce left-wing policies.

Ms Fernández de Kirchner's term ends in 2011, but the electoral defeat is threatening to cause a political crisis and will make it difficult for her to continue her present political course. The popularity of the president has suffered because she has been unable to deliver on her promise to reduce poverty. In addition, she is involved in a dispute with the country's farmers on a planned increase of export duties on agricultural products.