By Sergio Goncalves and Catarina Demony

LISBON (Reuters) -Portugal's centre-right Democratic Alliance was poised to finish first in Sunday's parliamentary election, just ahead of the incumbent Socialists but short of an outright majority, exit polls showed, pointing to tough negotiations ahead with the far-right.

The populist, far-right Chega party appeared on course to more than double its result in the last election in early 2022, when it won 7.2%.

It is likely to play a kingmaker role in post-election talks. However, the Democratic Alliance (AD) has so far ruled out any deal with Chega, which could make for an unstable government.

Polls published by the three main television channels SIC, RTP and TVI put the AD in the 27.6%-33.0% range, with the Socialist Party trailing slightly behind with between 24.2% and 29.5% of the vote.

Polling stations closed at 8 p.m. (2000 GMT).

The election was triggered by Socialist Prime Minister Antonio Costa's resignation amid a graft investigation four months ago.

The centre-left Socialist Party and the Social Democratic Party (PSD), which leads the newly-created AD, have alternated in power since the end of a fascist dictatorship five decades ago.

Issues dominating the campaign in western Europe's poorest country include a crippling housing crisis, low wages, sagging healthcare, and corruption, seen by many as endemic to the mainstream parties.

(Reporting by David Latona, Catarina Demony and Sergio GoncalvesEditing by Andrei Khalip, Frances Kerry, Christina Fincher and Giles Elgood)