HELSINKI (AP) — Finns will be voting Sunday to fill the country's 200-seat Eduskunta parliament after a campaign that saw debates over the country's generous welfare model, its rapidly aging population and how far to go to fight climate change.

Here's a look at the key issues and the main players in the election:

JUST THE FACTS

Some 4.5 million people are eligible to vote Sunday in Finland and will be choosing between 19 political parties and movements. Polls open at 0600 GMT (2 a.m. EDT) and close at 1700 GMT (1 p.m. EDT).

Early voting is popular. Over 1.5 million people, or 36% of eligible voters, had cast their ballots in advance by the April 9 deadline. The results of that early vote will be published as soon the polls have closed, and fuller preliminary results are expected with a few hours later Sunday night.

MAIN CONTENDERS

Finland's center-left Social Democratic Party tops a recent poll with 19% support, according to a poll this week commissioned by Finnish public broadcaster YLE. It would still need to find coalition partners if it ended up trying to form the next government.

Led by Antti Rinne, a former finance minister, the Social Democrats plan to raise taxes and increase spending to preserve a welfare system that is under huge strain. The party has also vowed to continue the country's pro-European Union stance.

Other key parties include the populist Finns Party led by Jussi Halla-aho and the National Coalition Party, led by Petteri Orpo, which took second and third places in the poll with 16.3% and 15.9% support respectively. They are trailed by the Center Party and the Greens, who have strong urban support and back moves to fight climate change.

Finland's outgoing center-right coalition government, led by Prime Minister Juha Sipila of the Center Party, pushed through an austerity package that has helped Finland return to growth and improve public finances after a three-year recession.

ELECTION TOPICS

Tackling climate change is a priority in a Nordic country with one-third of its territory above the Arctic Circle. Lawmakers last month voted to completely phase out burning coal by 2029. There have been calls for other actions to fight global warming, such as boosting the number of electric vehicles, cutting meat consumption through taxes or switching to more vegetarian food in public places like schools.

The populist Finns Party, meanwhile, has broadened its appeal to those who reject such sacrifices in the name of climate change.

Finnish voters have also been debating how best to preserve the country's health and social system, which for years has topped global quality-of-life and happiness rankings and created a world-renowned education system.

There are some divisions over proposed reforms, which are getting more urgent since the country's population of 5.5 million is rapidly aging. One plan aims to improve efficiency and reduce public spending by offering Finnish municipalities more freedom to choose between public and private providers for social needs and health care.

FINLAND'S OTHER BIG POLITICAL JOB

Finland will take over the rotating six-month presidency of the European Union on July 1.