Hopes have risen of a breakthrough in the stalled process of EU enlargement in the western Balkans after Bulgaria’s opposition agreed to support lifting the country’s veto on the start of accession talks with North Macedonia.

Boyko Borisov, a former Bulgarian prime minister, said his centre-right GERB party would vote in favour of beginning the EU negotiations. If adopted by Bulgaria’s parliament, that would also unlock membership talks with Albania ahead of a summit of EU leaders on Thursday and Friday.

“This is the most correct decision for the future of the Balkans, the EU and Bulgaria,” said Borisov. “We will not remain on the dark side of Eurasia, we will not allow Putinisation.”

The move marks a U-turn for Borisov, who blocked the talks with North Macedonia in 2019 in a dispute about the former Yugoslav country’s interpretation of Balkan history.

Kiril Petkov, Bulgaria’s reformist prime minister, had been poised to strike a deal with Skopje unlocking the talks when one of the parties in his coalition pulled out in protest over the issue earlier this month, leaving him clinging on to power.

A vote on enlargement talks could be held in parliament on Thursday, with GERB’s support being enough to lift Sofia’s veto.

European officials fear blocking EU enlargement would create political instability in the western Balkans and disillusionment about the region’s western orientation, which could be exploited by Russia.

In a further sign of possible movement, North Macedonia, Serbia and Albania on Wednesday confirmed they would take part in a summit in Brussels tomorrow with EU leaders, a day after threatening to not attend the meeting over Bulgaria’s opposition to North Macedonia’s candidacy.

“We’ll attend the EU Council meeting,” Albania’s prime minister Edi Rama said, adding that Bulgaria’s stance was akin to “kidnapping” and “destroys” the “spirit of Europe”.