As polls open at 7 am (0500GMT) in parliamentary elections on Sunday, Poland's ruling nationalist Law and Justice (PiS) party is hoping to win an unprecedented third term in office. Voting in the closely watched race ends at 9 pm (1900GMT), and the first results are due later in the evening.
The previous election in 2019 saw the reelection of a majority nationalist conservative United Right (ZP) coalition government, without a majority in the Senate.
Poland has a party-list PR voting system for its 460-seat lower house of parliament. Parties win seats based on the aggregate vote for their candidates in each constituency and then spread the seats to candidates with the highest totals. For the 100-seat Senate, candidates are elected on a first-past-the-post basis.
The system is a party-list proportional representation using the D'Hondt method in multi-seat constituencies.
There is a 5% threshold for parties and 8% for coalitions to win seats in parliament.
The elections are accompanied by a four-question referendum. One question asks Poles if they want the EU-imposed "admission of thousands of illegal immigrants from the Middle East and Africa."
Critics argue that the ruling PiS has tilted the election system through adjustments which have increased the voting power of rural voters.
In March, President Andrzej Duda signed into law a bill changing the electoral code, including boosting the number of polling stations and requiring local authorities to provide free transportation on polling day for the elderly.
If the opposition Civic Platform (PO) wins, Poland will likely mend fences with the EU and reverse PiS' judicial reforms and also many of its more socially conservative policies, for example on abortion. Both sides are committed to supporting Ukraine, but the PiS has wavered in recent weeks, seeking to fend off rising support for the pro-Russian far-right party, Confederation.
The PiS has been polling around 36% and the opposition coalition Ciivix Coalition (KO, headed by PO) at around 30%.
Other players include three smaller players, all with 9-14% in polls: Confederation, an economically libertarian and socially conservative party, the Third Way coalition, made up of the People's Party and a movement led by a television celebrity, and the Left, a coalition of three parties.
