By Sergio Goncalves
LISBON, Jan 28 (Reuters) - Portugal's ruling Socialists have lost more of their lead to the main opposition party, the centre-right Social Democrats (PSD), in two opinion polls released on Friday two days before Sunday's snap election.
The contest remains wide open. Analysts say the election is likely to worsen political volatility and could produce a short-lived government as no party or known alliance is seen gaining a working majority.
Premier Antonio Costa's centre-left party dropped to 35% support, according to a survey by ISCTE-ICS pollsters for TV channel SIC and newspaper Expresso, from 38% a month ago, while the PSD rose to 33% from 31%.
The gap between the two is smaller than the poll's 3.1% margin of error, meaning they are in a technical draw. A different poll earlier this week showed the PSD leading by a narrow margin.
It leaves each of them distant from a parliamentary majority, which under the proportional representation system equates to between 42% and 45% of the vote.
Another survey, by Catolica pollsters for TV channel RTP, Antena 1 radio and Publico newspaper, showed PS at 36%, down from 37% a week ago. The PSD remained steady at 33%.
In October, Costa's two former allies - the Communists and Left Bloc - sided with right-wing parties to reject the minority government's budget bill, triggering the snap election.
In the ISCTE-ICS poll, the far-right party Chega, the pro-business Liberal Initiative and the Communist-Greens alliance CDU saw support at 6% each, and any of them could become the third-largest force in parliament.
It gave 5% to Left Bloc, 2% to the People-Animals-Nature (PAN) party, while the right-wing CDS-PP and eco-Socialist Livre were on 1% each.
In the Catolica poll, Liberal Initiative, Chega and Left Bloc would win 6% each and CDU 5%. The CDS-PP, Livre and PAN had 2% each.
ISCTE-ICE surveyed 1,003 people on Jan. 18-24, while Catolica surveyed 2,192 people on Jan. 19-26, with a margin of error of 2.1%. (Reporting by Sergio Goncalves; editing by Andrei Khalip and Angus MacSwan)
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