Warsaw, Poland (CNN) -- Poland's Interim President Bronislaw Komorowski has won a runoff election against Jaroslaw Kaczynski, twin brother of former President Lech Kaczynski, who was killed in a plane crash in April.
The Polish electoral commission said Monday that Komorowski garnered 53 percent of the vote versus Kaczynski's 47 percent.
Sunday's ballot was required under Polish law after an earlier round of voting failed to give either candidate more than 50 percent of the vote.
Both candidates addressed supporters in televised speeches from their campaign headquarters Sunday night, after exit polling showed Komorowski holding a slim lead.
Kaczynski had congratulated his rival on exit poll results, but had not conceded victory.
Komorowski said, "I congratulate Poland and I thank you from the bottom of my heart for turning out to vote in such large numbers."
The president in Poland is primarily a ceremonial figure, but he has the power to veto laws, and thus helps shape politics. Kaczynski, once prime minister, is a divisive figure in Polish politics. His far-right Law and Justice party ran on a nationalist platform with the slogan, "Poland comes first."
"Poland has to be a strong country, otherwise it will not exist," he said recently. "I want to tell everyone here that as president I won't just be the head of state -- I will look after the strength of the Polish nation."
Komorowski is a moderate who ran for the center-right Civic Platform.
"We have been on this road for 21 years together, and we have been right," Komorowski said on the campaign trail. "We have been moving toward democracy and navigating our way in a free economy."
The former president, his wife and more than 90 others were killed April 10 in western Russia on their way to a service commemorating the 70th anniversary of the Russian massacre of Polish prisoners of war in the village of Katyn.