European Commission President Jose Manuel Barroso, right, and Bulgarian Prime Minister Plamen Oresharski walk past the media at the European Commission headquarters in Brussels. (AP Photo/Eric Vidal)

Sofia - Final results of the EU vote in Bulgaria on Wednesday sparked talk of snap elections and renewed instability as they confirmed the ruling Socialists' poor showing.

The conservative opposition GERB party, led by ousted premier Boyko Borisov, won Sunday's vote with 30.4 percent support, ahead of the Socialists on 18.93 percent, the central electoral commission announced.

GERB will take six of Bulgaria's 17 seats in the European parliament, while the Socialists and their ruling partner - the liberal Movement for Rights and Freedoms (MRF), which finished an expected third with 17.27 percent - will each have four.

GERB's unexpectedly big victory and the Socialists' drop in support now spell trouble for Prime Minister Plamen Oresharski.

On Wednesday, MRF leader Lyutvi Mestan hinted that the results had dented his party's staunch backing for the cabinet, noting that Oresharski did not stand a chance to complete his four-year term in office.

He added he was open to discuss a cabinet reshuffle or a snap vote with the Socialists in the coming days.

The prime minister, who faced street protests to resign last summer, also faces a no-confidence vote in parliament on Friday, which was put forward by GERB and will hinge on the unpredictable ultra nationalists Ataka.

Two more parties passed the minimum threshold to enter the European parliament: a new populist formation Bulgaria Without Censorship (BBC) with 10.66 percent and two deputies, and the old-school conservative Reformist Bloc with 6.45 percent and one deputy.

Turnout was only 36.15 percent as many Bulgarians stayed away, disillusioned with widening poverty and corruption.