Bulgaria’s government was ousted in a vote of no confidence, throwing the country into further political turmoil and dashing hopes that it could help quickly relaunch the stalled EU enlargement process to the Western Balkans.

Bulgarian MPs voted 123 to 116 to oust Prime Minister Kiril Petkov, a reformist who has vowed to fight corruption and took a hard line against Russia’s invasion of Ukraine. Petkov had been prime minister for six months.

Petkov has been overruled in a dispute over a plan to remove Bulgaria’s veto over the start of EU membership talks with North Macedonia as well as differences over the budget. The county is now likely heading for its fourth election since April last year.

The vote of no confidence is a blow to EU leaders, who are due to meet in Brussels on Thursday to try to relaunch the enlargement process in the Western Balkans.

Earlier on Wednesday, Bulgaria’s main opposition party said it would support lifting the country’s veto on talks with the EU in North Macedonia. Boyko Borisov, a former Bulgarian prime minister, said his center-right GERB party would vote in favor, despite first exercising the right of veto three years ago in a dispute over Skopje’s interpretation of Balkan history.

Despite this sudden change, the GERB also continued its censure decision against the government. Petkov’s allies suspected that Borisov’s move on North Macedonia’s EU membership – which remains unpopular in Bulgaria – was a political trap.

EU officials fear that the continued postponement of EU enlargement could create political instability in the Western Balkans and lead to disillusionment over Brussels’ endorsement of the region’s Western orientation, which could be exploited by Russia. Petkov had backed EU sanctions against Moscow and sacked its defense minister after refusing to call the Russian invasion a “war”.

The lifting of the veto on the talks with North Macedonia would also have unblocked the negotiations with Albania. The two countries’ membership applications have been linked by the EU. The former has been an EU candidate country since 2005 with no progress in accession negotiations despite meeting many of the bloc’s membership conditions, mainly due to objections over expressions of national identity from the former -Yugoslav Republic first from Greece and then from Bulgaria.

The EU’s broader stance on eastward expansion has changed since Putin’s full-scale invasion of Ukraine began in February, following years of resistance to potential new members. The bloc is expected to agree to make Ukraine and Moldova official candidate countries this week, alongside renewed efforts to unblock the stalled process in the Western Balkans.

Petkov was close to reaching a deal with Skopje to unblock the talks when one of his coalition parties pulled out in protest at the issue earlier this month, leaving him without a majority.

Petkov could try to form a new majority. If he fails, which seems likely, it would be up to GERB to try, even though he is still seen as toxic by other parties given the widespread corruption during his time in power.

In the meantime, North Macedonia’s candidacy will remain frozen.

After hopes for a possible breakthrough were raised earlier, North Macedonia, Albania and Serbia said they would attend the Brussels summit on Thursday with EU leaders. They had threatened not to attend the meeting on Bulgaria’s position.