Passos Coelho, leader of the Social Democratic Party (PSD) and Paulo Portas leader of the Christian Democrats (CDS-PP) confirmed the decision at a presentation held in Lisbon on Saturday night.

The two pledged an open and positive campaign and opened the door to any independent candidates wishing to join their course.

The PSD-CDS coalition was formed in 2011 after the PSD failed to gather sufficient votes to govern with a majority.

The next general elections are expected to take place in the autumn, probably in October.