Term limits require the Baltic country's current head of state, President Dalia Grybauskaite, to step down after two five-year terms. The election to choose the popular Grybauskaite's successor could go to a second-round vote.
The campaign has focused on domestic issues such as the economy, corruption and social welfare, even though foreign policy and defense are two of the presidency's main purviews. The leading candidates include Prime Minister Saulius Skvernelis, 48; former banking economist Gitanas Nauseda, 54; and former Finance Minister Ingrida Simonyte, 44.
In recent public opinion polls, Simonyte has been in front with support from more than 26% of likely voters, but Nauseda and Skvernelis aren't far behind. Along with picking their president, voters on Sunday face a referendum on a constitutional amendment to allow dual citizenship for hundreds of thousands of Lithuanians living abroad.
A presidential runoff would be held May 26, the same day Lithuanians vote for their EU parliament representatives and another referendum on reducing the number of lawmakers in the 141-seat Seimas assembly.
Skvernelis, who was a police officer before he entered politics, has suggested opening a dialogue with Russia, a departure from the recent governments in Vilnius, and floated the idea of moving the Lithuanian Embassy in Israel from Tel Aviv to Jerusalem.
If the prime minister wins, it would be seen as "a concentration of political powers" for his ruling Peasant Greens Union party, said Tomas Janeliunas, a professor at the Institute of International Relations and Political Science at Vilnius University.
Grybauskaite's anti-Russia views, no-nonsense style and karate black belt earned her the "Iron Lady" label previously applied to Margaret Thatcher when she was British prime minister. Lithuania today is very different from the one Grybauskaite became president of in 2009.
"Ten years ago, our country was severely affected by the financial crisis and fully dependent on Russian gas, with no real existing NATO defense plans," she told The Associated Press. Now Lithuania is a "strong and prosperous state" that has diversified its energy supply and like its Baltic neighbors, joined NATO as well as the European Union, Grybauskaite said.
A vital job of successor will be staying alert to Russia's military activity in the Baltic Sea region, she said. "The geopolitical situation will remain tense," the outgoing leader said. "Therefore, further measures to increase military security, defense, and deterrence capabilities, fight aggressive propaganda, cyber and other hybrid threats will remain among the top priorities."