SOFIA, Bulgaria (AP) — A former Bulgarian Air Force officer who has called on the European Union to lift its sanctions against Russia won the most votes in the country's presidential election, but not enough to avoid a runoff, according to results released Monday.

With 95.17 percent of the ballots counted, Socialist-backed candidate Rumen Radev led the field with 26 percent of the vote. The candidate of the ruling center-right party, Parliament Speaker Tsetska Tsacheva, came in second with 22 percent, the Central Election Commission said.

Radev, 53, and Tsacheva, 58, will face off again during a second round of voting on Nov. 13.

They were two of 21 candidates seeking the largely ceremonial presidency in Bulgaria, which is the poorest member of the European Union. Corruption and poor economic prospects have fueled disillusionment among its 7.2 million citizens.

The Balkan nation's relations with Russia, the future of the European Union and increasing immigration since neighboring countries closed their borders to refugees and migrants fleeing Africa and the Middle East dominated the election campaign.

Radev, a former fighter pilot, has pledged to comply with Bulgaria's European obligations, if he is elected. But he also has said that "being pro-European does not mean being anti-Russian" and insisted that sanctions on Moscow need to be lifted.

Bulgaria joined NATO in 2004, but many in this Black Sea country still share deep historical and cultural ties with Moscow. Energy-strapped Bulgaria is also heavily reliant on Russian supplies.

In an attempt to soothe Bulgarians' fears of a migrant influx, Radev has said he would not allow "Bulgaria to turn into Europe's migrant ghetto."

Tsacheva is widely expected to continue the pro-Europe foreign policy of incumbent Rosen Plevneliev, if she emerges from the runoff as Bulgaria's first female president.

She called on voters Monday not to allow "Bulgaria to return to the dark past of ideological lies and the subordination to foreign interests." She made her remarks ahead of a meeting with leaders of right-wing parties who have pledged to support her next weekend.

Prime Minister Boiko Borisov said he would quit, if Tsacheva loses.

"If we lose the ballot, which I hope we won't, we will go for early elections, we will exit the government," Borisov told reporters after initial results from Sunday's first round were announced.

Borisov's coalition government has restored political stability in Bulgaria after months of anti-corruption protests, but its popularity has faded due to the slow pace of reforms to eliminate graft and to overhaul the judicial system.