SOFIA (Reuters) - Bulgarian center-right leader Boiko Borisov, hoping to return to government at elections on Sunday, said on Tuesday Bulgaria should work to deepen its integration within the European Union as quickly as possible.

Former Bulgarian Prime Minister and leader of centre-right GERB party Boiko Borisov speaks during an interview with Reuters in Sofia, Bulgaria, March 21, 2017. REUTERS/Stoyan Nenov

The GERB party of Borisov, 57, who has led two center-right governments since 2009, is vying with the leftist Socialists who take a more sympathetic line toward former Soviet masters in Moscow.

“Bulgaria’s membership of the EU, even if it’s not fashionable to talk about it now in Bulgaria, is the best thing to happen to us,” Borisov told Reuters in an interview.

Bulgaria became an effective transit route into the EU for migrants heading largely from the Middle East and South Asia, a development that aroused great controversy.

The EU itself faces trying times with anti-EU parties competing for influence at elections in France and Germany this year. Dutch anti-immigration and anti-EU politician Geert Wilders finished a strong second place in elections this month.

Borisov’s government resigned in November after its candidate lost the presidential polls to the pro-Russian, Socialist-backed Rumen Radev, and Bulgaria is currently in the hands of a caretaker administration.

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CORRUPTION

The pro-EU and pro-market GERB, has maintained a tiny lead in opinion polls over the Socialists, who favor a bigger role for the state in the economy.

But with every fifth Bulgarian yet undecided, the vote is unpredictable and the Balkan country is likely to have another fragile coalition government.

Migration has been a focus of tensions with the EU and an issue in domestic politics.

Migrant inflows through Bulgaria, which lays on one of the routes to northern Europe, eased significantly last year. But increased tensions between Ankara and the EU, have renewed fears that Turkey back down on a deal that has curbed the flow of migrants from its territory.

Bulgaria, a Black Sea nation of 7.2 million people, joined the EU in 2007 but still depends almost entirely on Russia for its energy supplies and Russian tourists are an important source of revenue. It remains under close EU scrutiny on issues of corruption and organized crime that have eaten at his support, now at 29.8 percent compared to 32.7 percent in 2014 elections.

“We are heading in the right direction. Now we have to make the utmost effort in combating corruption, in combating smuggling...These are things we can do,” he said.

Relations with Russia are a sensitive political issue in a country that was closely allied to Moscow through the Cold War. Bulgarians share a similar language and the Cyrillic alphabet with the Russians.

The Socialists, built on the former Communist Party, pledge to block any extension of EU sanctions imposed on Russia over its 2014 annexation of Crimea in Ukraine.

“We continue to be against the Crimea (annexation), because when borders are changed by force, Bulgaria becomes vulnerable,” Borisov said.

(This version of the story corrects paragraph six to show that Radev was backed by the Socialist party, not that he was is a member of the party)