WARSAW, Poland (AP) — Poland is holding an election Sunday that will chart the way forward for the European Union's fifth most populous country and its sixth biggest economy.

The outcome will determine whether the right-wing Law and Justice party will win an unprecedented third consecutive term in power or a combined opposition can win enough support to oust the ruling party that has led Poland for eight years.

A referendum on migration, the retirement age and other issues is being held simultaneously, which the opposition says is an effort to mobilize the ruling party's electorate.

Here are the basic facts about the vote, the referendum and the appointment of a new government.

Some 29 million Poles aged 18 and above are eligible to vote.

They will choose 460 members of the lower house, or Sejm, and 100 for the Senate for four-year terms.

More than 31,000 voting stations across Poland will be open from 7 a.m. to 9 p.m. (0500-1900 GMT) on Sunday. Over 400 voting stations will operate abroad.

Exit poll results by global polling research firm Ipsos will be announced on state broadcaster TVP and commercial stations TVN and Polsat when polls close at 9 p.m. (1900 GMT). The margin of error is plus or minus 2 percentage points.

Individual parties need to get at least 5% of votes to win seats in parliament, coalitions need at least 8% of votes.

Volunteers affiliated with the political parties will be monitoring the election at voting stations. The Organization for Security and Cooperation in Europe has also deployed a limited election observation mission.

The State Electoral Commission may take two, even three, days to announce full official results of the elections.

Opinion polls suggest the ruling Law and Justice party will win the most votes, but not enough for a majority in Parliament.

A referendum with four questions is being held in parallel with the parliamentary vote. Voters are being asked their views on whether to accept migrants, keep a new wall on the border with Belarus, raise the retirement age and sell off state assets.

More than 50% of eligible voters need to take part to make the referendum legally binding. Some opposition groups are calling on voters to boycott it.

There are five parties or coalitions that are expected to reach the threshold for seats in Parliament:

LAW AND JUSTICE — The right-wing party that has governed Poland since 2015 is led by Deputy Prime Minister Jaroslaw Kaczynski, 74, the country's most powerful politician.

Since taking power, the conservative nationalist party has tightened Poland's abortion laws and built a wall on the border with Belarus intended to stop irregular migration. It vows to continue its anti-migration policy and to oppose EU plans on sharing out responsibility for migrants.

The government has also clashed with the EU over violations of democratic principles, leading to the freezing of billions of euros of pandemic recovery funds intended for Poland. Law and Justice wants less EU authority in the 27 member countries.

It has boosted military spending and been a strong supporter of Ukraine after the full-scale Russian invasion, though the relationship has been strained recently over Ukrainian grain shipments through Poland.

The government gained popularity for cash benefits for families and retirees and has vowed to expand those programs if reelected.

CIVIC COALITION — A centrist coalition dominated by the Civic Platform party led by Donald Tusk, 66, a former Polish prime minister and former EU president. The coalition also includes three smaller parties including the Greens.

It vows to restore stronger ties with the EU and heal rifts it accuses the governing party of creating in Polish society. It also accuses the government of eroding the rule of law in Poland and promises to liberalize the abortion law and free state media from government control.

It is also promising raises of 30% to teachers, who are leaving the profession due to low wages. With Civic Coalition being a broad coalition, its member parties have different priorities. The Greens want to ban logging in critical forests while a pro-market party in the coalition is vowing tax cuts.

Tusk led two huge marches of supporters in Warsaw this year.

THIRD WAY — A coalition of the centrist Poland 2050 party and the agrarian Polish People's Party, PSL.

Third Way has suggested a national referendum on liberalizing the strict abortion law. It has promised to increase spending on health care and education, pursue family-friendly policies and support small businesses with a simpler tax system.

CONFEDERATION LIBERTY and INDEPENDENCE — A hard-right, anti-EU coalition that includes radical nationalists as well as free-market libertarians. Some leaders have made antisemitic and anti-LGBTQ+ statements, which they sought to play down during the campaign.

They are anti-migration and want stronger protection of the Polish and EU borders. They also want less support for Ukraine in its struggle against Russia's aggression. They promise lower taxes and are against abortion.

Polls suggest the current government is likely to need the support of Confederation to stay in power.

NEW LEFT — Social Democratic party that wants a clear separation of state and church and a tax on the Catholic Church's assets in Poland. It wants to relax the abortion law to allow women to undergo the procedure up to the 12th week of pregnancy. It has also called for cheaper housing for young people.

Poland's Constitution requires the nation's president to convene the new parliament within 30 days of the election. At that session, the government tenders its resignation, but stays on in a caretaker role.

The president tasks one of the political leaders, usually from the party that won the most votes, to form a new Cabinet. The prime minister-designate must present a Cabinet and program and get majority support in the Sejm in a vote of confidence within 14 days.

If that fails, the lawmakers must designate a new candidate. If that also fails, the president chooses a third candidate. If all three attempts fail, the president calls for new parliamentary elections.

Tusk says the election is the most important one since Poland shed communism in 1989. He says it's about Poland's future in the EU and that Law and Justice remaining in power could result in Poland leaving the union which it joined in 2004.

The current government says it has no plans to bring Poland out of the EU, just reduce Brussels' influence on the member countries. It has alleged that if Tusk's coalition takes power, Poland will be flooded with migrants, which the opposition rejects as scaremongering.

All sides are in favor of staying in NATO, which Poland views as a vital security guarantee against Russia. However, analysts say Poland's support for Ukraine could be weakened if the Confederation party ends up in a kingmaker role.