Romania’s prime minister conceded defeat on Sunday night after an extremely close presidential runoff against an ethnic German Transylvanian mayor. Victor Ponta had been the favorite to win, but was narrowly edged out by Klaus Iohannis, the mayor of the city of Sibiu, who has promised a crackdown on corruption.

Ponta said he had personally congratulated Iohannis. “We are a democratic country,” Ponta said outside the headquarters of his Social Democratic party two hours after polls closed. “The people are always right.”

Ponta called on 15,000 protesters gathered outside his offices to listen to his message in an apparent attempt to defuse tensions encountered by expat Romanians voting abroad.

Exit polls put the results at neck and neck. The official result is expected on Monday.

About 300,000 Romanians who live overseas voted, many against the government. There were protests that they had been unable to vote in the election on November 2 that led to the runoff.

“Romanians, you were heroes today,” Iohannis said before Ponta’s concession, calling on authorities to count the vote correctly. “The vote was phenomenal!” He went on to say that voters had come “out of their houses to defend the right to vote” 25 years after the Romanian revolution.

Some Romanians waved toothbrushes in protest at long waits at polling stations abroad. Romanians living overseas had to vote at polling stations in their adopted countries, and thousands grew exasperated when they had to stand in line for hours in cities such as Paris, London, and Munich during the first round. Some were unable to vote. The government said it had improved the voting procedure this time.

Ponta led by 10 percentage points in the original vote, and corruption probes of senior Ponta aides appeared not to have dented the 42-year-old former prosecutor’s chances. Iohannis, 55, has promised an independent justice system if he becomes president.

The winner will replace Traian Basescu, who is stepping down after 10 years. In Romania, the president is in charge of foreign policy and defence, and names key prosecutors and the chiefs of intelligence services.

• This article was amended on 17 November 2014. An earlier version of the headline referred to Klaus Iohannis as ethic, rather than ethnic, German mayor.

