WARSAW, Poland — A year before Poland’s general election, the country’s main opposition leader suggested that countries led by nationalist parties could open negotiations to leave the European Union to pressure it to return powers to member states.

“The European Union must be changed. This is my deep conviction, shared by my party and, I believe, very many Poles,” Jarosław Kaczyński, the leader of the national-conservative Law and Justice, said Wednesday at an economic forum in southern Poland.

He said EU institutions like the European Commission, the EU’s executive body, have too much influence, but that upcoming elections in France and Spain, which could bring far-right politicians to power, could open the way for discussions about change.

He offered several ideas for change, including having national parliamentarians monitor how often EU bodies break EU law.

But as a last resort, he suggested that countries seeking reform could conclude a new treaty that would take effect at a later date while simultaneously opening EU withdrawal negotiations. He presented that as a way to pressure other countries and EU bodies to accept changes.

His remarks sparked criticism from senior government figures in Poland.

“Jarosław Kaczyński has just announced that Poland should begin negotiations on the conditions of leaving the European Union,” the pro-European prime minister, Donald Tusk, wrote on X.

Kaczyński accused Tusk of misrepresenting his intentions. “We want the union to benefit not the elites, but the ordinary citizens,” Kaczyński shot back on X.

Poland, a key country on NATO’s eastern flank and one of the EU’s fastest-growing economies, has gained strategic importance in recent years, partly through its crucial role in supporting Ukraine.

Kaczyński’s party led Poland between 2015 and 2023, leading to major conflicts with EU institutions over the rule of law and human rights.

One year ahead of general elections, polls indicate that Kaczyński could bring his party back to power if he allies with smaller far-right groups that have been on the rise in Poland in recent years.

Kaczyński said the EU reform he is advocating was focused on “improving citizens’ living conditions, lowering energy prices, strengthening security, pursuing a responsible migration policy and an ambitious economic and agricultural policy without unnecessary bureaucracy.”

Foreign Minister Radosław Sikorski said Kaczyński’s remarks should help Polish voters understand the consequences of choosing the far-right.

“I thank Jarosław Kaczyński for his honesty,” Sikorski said.