Strict COVID-19 measures during the pandemic, political scandals involving several key members of the cabinet and an influx of migrants from neighbouring Belarus have hurt the popularity of Prime Minister Ingrida Šimonytė's government, which took office in 2020.
The vote in Lithuania, which borders Russia's Kaliningrad exclave to the west and Belarus to the east, comes at a time when Russia's war in Ukraine is fueling greater fears about Moscow's intentions, particularly in the strategically important Baltic region.
It will set the political tone for the next four years, but despite a possible shift to the left analysts say there won't be any significant change in Lithuania's foreign policy.
The European Union and NATO member is a staunch supporter of Ukraine.
Voters in dozens of electoral districts will choose between the two leading candidates from the first round to complete the new 141-seat parliament, known as the Seimas.
Prime Minister Ingrida Šimonytė is hoping a second round of elections will favour her party. (AP PHOTO)
The opposition Social Democrats, led by Vilija Blinkevičiūtė, came out of the first round with an edge two weeks ago, taking 20 of the first 70 seats to be decided. That put them two seats ahead of Šimonytė's Homeland Union party.
Blinkevičiūtė has said that she and the centre-left Democratic Union, which took eight seats, would attempt to form a coalition together with a smaller third party.
The three parties, which so far have 34 lawmakers in total, have said they would support each other's candidates in the second round.
But the centre-left parties could lose their lead, and their ability to form a stable government could depend on a new party that many consider a pariah.
The Nemuno Aušra party came in third in the first round, with 15 seats. Its leader Remigijus Žemaitaitis had to resign from parliament earlier this year for making antisemitic statements.
A strong showing for Nemuno Aušra could open the way for the prime minister's party to form a minority government.
"Nobody can claim to have an obvious majority after the first round," said Mažvydas Jastramskis, a political analyst at Vilnius University's Institute of International Relations and Political Science.
Šimonytė's Homeland Union won 18 seats in the first round and its coalition member, the Liberal Union, took eight. Both have several dozen candidates leading in run-offs, but they aren't in a position to win the 71 seats needed for a majority.
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