BUCHAREST, Romania — Romania's presidential runoff election was extremely tight, according to exit polls Sunday, with a prime minister promising stability and a city mayor vowing to fight corruption running neck and neck.

Prime Minister Victor Ponta was slightly ahead, two exit polls said, while two others gave Sibiu Mayor Klaus Iohannis, an ethnic German, a slight lead and one poll said it was 50 percent each.

"Today I made Romania powerful!" Ponta posted on his official Facebook page. "Thanks for your support!"

A party leader said he had scored a narrow victory. The final results could be swung by 300,000 Romanians who live overseas and voted Sunday, many against the government. There were protests that they had been unable to vote in the Nov. 2 election that led to the runoff.

"Romanians, you were heroes today," Iohannis said, calling on authorities to count the vote correctly. "The vote was phenomenal!"

Iohannis praised voters, saying they had come out "of their houses to defend the right to vote" 25 years after the Romanian revolution.

Thousands of Romanians massed in front of government offices in Bucharest waving flags with the center ripped out, a symbol of the 1989 anti-communist revolt. Others gathered in the city of Cluj after voting ended in support of expat voters.

On Sunday, some Romanians waved toothbrushes to protest long waits at polling stations abroad and thousands protested in Munich, according to Mediafax news.

Romanians living overseas must vote at polling stations in the countries where they are, and thousands of expats protested after 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 says it has improved the voting procedure this time at facilities, including Romanian embassies.

Ponta led by 10 percentage points in the Nov. 2 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.

Election results were expected Monday, and the winner will replace President Traian Basescu, who is stepping down after 10 years.

In Romania, the president is in charge of foreign policy and defense, and names key prosecutors and the chiefs of intelligence services.

Officials said turnout was about 62 percent, around 10 percent higher than during the Nov. 2 vote.