Unlike Spain or Greece, debt-ridden Portugal has not seen the rise of a protest movement strong enough to challenge the traditional parties at the polls, with surveys so far predicting a neck-and-neck race.

A survey for RTP public television published late Saturday said the alliance of the centre-right Social Democrats (PSD) and the conservative CDS-PP party had the backing of 43 percent of those polled, “giving it the possibility of wresting an absolute majority”.

It said the Socialist Party led by former Lisbon mayor Antonio Costa was supported by 33 percent of the 936 people interviewed for RTP by the Portuguese Catholic University.

One quarter declared themselves undecided.

Another survey for the Publico daily and TVI television channel said the ruling coalition would win 37.5 percent of the vote against 32.8 percent for the Socialists.

Portugal has not seen such a tight electoral race since it became a democracy in 1974.

It is still recovering from its 2011 economic crisis when it became the third eurozone country after Ireland and Greece to be bailed out.

It left the bailout scheme in May 2014 but only after implementing stringent austerity measures in return for funding.