Poles began voting on Sunday in a presidential election which had originally been scheduled for May but was delayed by the coronavirus pandemic.
President Andrzej Duda, a 48-year-old conservative backed by the ruling party, is running against 10 other candidates as he seeks a second five-year term.
Most recent polls showed that no single candidate is likely to reach the 50% required to avoid a run-off, in which case the two who poll the highest number of votes will face each other on July 12.
Polling stations remain open until 9pm (1900 GMT), and exit polls will be announced immediately afterwards. The final official results are expected by Wednesday at the latest.
Poland has not been as badly hit by the virus as many countries in Western Europe, and most people were voting in person, although they were required to wear masks and observe other hygiene rules.
There was also a postal vote option, while thousands in some south-western regions with higher numbers of infection were also required to vote by mail.
As of Sunday, there were about 34,000 confirmed cases of Covid-19 in the nation of 38 million people, with some 1,400 deaths.
The election is taking place amid deep cultural and political divisions.
Mr Duda, who is backed by the ruling Law and Justice party, has run a campaign which focused on defending traditional values in the mostly Catholic nation while promising to raise living standards on a par with those in the West.
He took a position against same-sex marriage and adoption and denounced the LGBT rights movement as a dangerous “ideology”.
That kind of rhetoric – along with laws that have given the nationalist and conservative Law and Justice party much greater control over the justice system and the harnessing of public media as a tool to promote the government’s image – have raised concerns among some that Poland is following Hungary in eroding democratic foundations.
Mr Duda’s strongest challenge comes from Warsaw mayor Rafal Trzaskowski, also 48, who is backed by the centrist Civic Platform party.
On the campaign trail, Mr Trzaskowski has promised to retain Law and Justice’s popular spending programmes while vowing to restore constitutional norms.
He entered the race late after the election originally scheduled for May 10 was scrapped due to the pandemic.
Mr Duda’s once strong support, bolstered by adulatory coverage in public media, began to slip once restrictions were lifted and other candidates could campaign.
Polling ahead of Sunday’s vote suggested that Mr Duda is the front-runner but might not reach the 50% needed to win outright. Polls also showed that he would have a more difficult time in a run-off given that many opposition votes would be expected to consolidate against him.
The other candidates include Szymon Holownia, a TV personality and journalist who had once studied to be a priest. He is unaffiliated with any party and has generated some enthusiasm among those tired of years of bickering between Law and Justice and Civic Platform, the country’s two main parties.
Also in the running are Robert Biedron, a left-wing politician who is Poland’s first openly gay presidential contender; Wladyslaw Kosiniak-Kamysz, the head of an agrarian party; and Krzysztof Bosak, a member of the far-right Confederation party.