WARSAW, Poland (AP) ― Poles will vote in parliamentary elections that will determine whether the country continues on its conciliatory course with Russia and Germany, or whether it returns to a more combative stance with those historic foes.

Before Sunday’s voting, polls showed Prime Minister Donald Tusk’s centrist and pro-EU party in the lead, but facing a tough challenge from Law and Justice, the conservative and nationalistic party of Jaroslaw Kaczynski.

Kaczynski, a former prime minister who was unseated by Tusk in 2007, made several anti-German comments in recent days, indicating that his Law and Justice party seems prepared to resume a confrontational tone with the large neighbor to the West.

Ties with Russia will also be determined by who wins. Tusk has been trying to mend ties with Russia, the powerful Eastern neighbor whom many Poles still fear and resent.

Polish memories remain strong of Moscow’s invasion of Poland’s eastern half in 1939 and its dominance of the country during the Cold War. More recent sources of friction have stemmed from Poland’s support for the pro-Western Orange Revolution in Ukraine in 2005 and its acceptance of a Bush-era plan for a U.S. missile defense base in Poland ― a project that outraged Russia but which President Barack Obama has since scaled back.

A government led by Kaczynski would certainly alter the tone. His twin brother, President Lech Kaczynski, died in a plane crash in Russia in 2010 along with 95 others, and Kaczynski has suggested that Tusk and Russian authorities are to blame for that tragedy.

Tusk has said he fears that Kaczynski would seek revenge on those whom he blames should he return to power.

The plane crashed as Lech Kaczynski and his delegation were on their way to honor 22,000 Polish officers killed during World War II by Soviet dictator Josef Stalin’s secret police, a crime known as the Katyn massacres.

Voters in this country of 38 million will elect 460 lawmakers to the lower house of parliament, the Sejm, and 100 to the Senate. The party that wins the most seats will be charged with forming a government; in the absence of an outright majority it would need to seek a coalition partner.

Polling stations across the country will be open from 7 a.m. to 9 p.m. Exit polls will be released when polls close, but official results will come several hours later.

The vote will be a major test for Tusk, who has presided over a period of remarkable growth and helped steer the state during Poland’s worst tragedy in decades ― the 2010 plane crash in Russia that killed President Kaczynski and 95 others, many of them political and military leaders.

To his supporters, Tusk is a moderate leader who has promoted stability and good relations with Germany ― which occupied Poland throughout World War II ― Russia and the European Union. They point to the fact that the economy has grown steadily on his watch, even when the rest of Europe fell into recession in 2009.

His opponents accuse him of lacking the courage to make ambitions reforms in a country with significant problems, like high unemployment at nearly 12 percent and heavy state regulation that stifles businesses. The budget deficit has also grown during his term, and economists say Poland’s current growth of around 4 percent will slow next year.

Several small parties are also vying for support. However, the main battle pits Tusk’s pro-market and pro-EU vision against that of Kaczynski. Kaczynski favors more state involvement in the economy to help the disadvantaged.

He is much more skeptical of outside powers and employs a strongly patriotic message. In past days, he provoked an uproar in Poland with a new book in which he accuses Germany of trying to subjugate Poland.

If Tusk’s Civic Platform wins on Sunday, it would make history by becoming the first to ever win two consecutive terms since the fall of communism in 1989, underlying the growing stability that has replaced the political turmoil of the early years of democracy.

However, polls show it unlikely to win enough votes to have an outright majority in parliament, meaning it would likely need to find a coalition partner. It had a good relationship with its junior partner of the past four years, the farm-based Polish People’s Party.