Jarosław Kaczyński, the de facto ruler of Poland | Janek Skarzynski/AFP via Getty Images Poland’s PiS smashes opposition in European election vote The vote sets up a decisive battle in national parliamentary elections this fall.

WARSAW — Poland’s ruling Law and Justice (PiS) party won a crushing victory over a coalition of opposition parties in Sunday’s European ballot — leaving it in a strong position for this fall’s national election.

With 95.9 percent of the votes counted, PiS had 46.01 percent of the vote, and the opposition European Coalition had 37.87 percent. One other party made it over the 5 percent threshold — the left-wing Wiosna with 6.02 percent. That's a significantly better outcome for PiS than predicted by an exit poll announced immediately after polls closed on Sunday evening.

That kind of dominance of the two largest parties is unusual among EU countries, where the vote tends to be split among a larger number of parties, and shows Poland’s deep political polarization.

The turnout was 45.42 percent — easily the highest for any European election since Poland joined the EU in 2004. It's a sign of how the fierce battle between PiS and the opposition for control of the country galvanized voters in the European contest.

Poland is also on track to send the highest proportion of Euroskeptics to Brussels, with 53 percent of the vote and more than half the seats going to Euroskeptics (PiS is counted in that category as a soft Euroskeptic).

PiS cheers

Jarosław Kaczyński, the leader of PiS and Poland’s de facto ruler, celebrated his party’s strong result — the most it's ever won in any election — and cements his role as the country's most powerful politician

“Today is a very important day,” he told cheering supporters on Sunday evening, adding: “We have to remember that the decisive battle for the future of our country will take place this autumn and we also have to win — and win by even more than now.”

The outcome is a disappointment for the Coalition, as European elections tend to mobilize voters in larger cities that are the grouping’s natural supporters.

“I’m surprised,” said Radosław Sikorski, a former Polish foreign minister who won an EP seat for the European Coalition, “because PiS saw defeat after defeat on European issues.”

The result makes clear that this fall’s election will be a fight between PiS and the Coalition, but the opposition is going to have a mountain to climb to unseat Law and Justice.

“We united the opposition, but we know that it’s only the beginning of our path,” said Grzegorz Schetyna, the leader of the center-right Civic Platform party, who cobbled five opposition parties into the European Coalition. “We showed that we can and we must be together. That’s the key to victory in October.”

There had been doubts whether the Coalition would continue to function in the national election, but Schetyna’s comments indicate it plans to remain united, despite the deep program divisions in a grouping that runs from the Christian democratic Civic Platform to the ex-communist Democratic Left Alliance.

Wiosna, created by charismatic former MP Robert Biedroń, tried to woo left-wing, big-city voters with a secular, pro-LGBTQ platform. Despite a strong performance in early opinion polls, the party only barely made it in to the European Parliament.

That didn’t stop Biedroń from claiming victory.

“We did it. We’re the third political force in Poland,” he said.

Some big Polish names in the European Parliament include five former prime ministers running for the Coalition: Jerzy Buzek, Włodzimierz Cimosiewicz, Marek Belka, Ewa Kopacz and Leszek Miller. Prominent MEPs Roża Thun and Danuta Hübner will also be back in the Parliament.

Beata Szydło, a former PiS prime minister, won a seat with 471,000 votes — the most in the country, according to the exit poll. At least six PiS ministers also won seats. Jacek Saryusz-Wolski, a PiS MEP who challenged Donald Tusk when he was seeking a second term as European Council president two years ago, will also return. Ryszard Czarnecki, a former vice president of the Parliament, appears not to have won a seat.

Zosia Wanat contributed reporting.

This article has been updated with the latest vote count.