LISBON (Reuters) - Portugal's ruling Socialists maintained their lead position ahead of Sunday's election in an opinion poll published on Wednesday, but remained short of a majority, while support for the main opposition surged.
Prime Minister Antonio Costa's center-left party, currently ruling with support from two far-left, eurosceptic parties, stood at 37% of voting intentions in the survey by the Catolica University pollsters for Publico daily and RTP television.
The main opposition Social Democrats fetched 30%, up from 28% in Catolica's previous poll in May, when the front-running Socialists had 39%.
When compared to other polls since May, the Socialists' lead has about halved from as much as 15 percentage points.
If the Socialists fail to win full majority they would need the support of another party to pass legislation. Costa's allies in the current legislature, Left Bloc and the Communists, stood at 10% and 6% respectively.
Just one large enough ally is now likely to be needed to secure a majority, and analysts say souring relationships with the hard-left could prompt Costa to seek a new partner or partners.
Catolica surveyed 3,226 people on Sept. 26-30, with a margin of error of 1.7%.