European Union officials have warned that the bloc “is at risk of collapse” unless it challenges a ruling by Poland’s top court over the supremacy of EU law, which is seen as a central pillar of European integration.

Vera Jourova, the Czech EU commissioner, said Monday: “If we don’t uphold the principle in the EU that equal rules are respected the same everywhere in Europe, the whole Europe will start collapsing. That is why we will have to react to this new chapter which the Polish constitutional court started to draw.”

Large rallies were held across Poland over the weekend in support of EU membership following the ruling by the country’s Constitutional Tribunal last Thursday.

An estimated 100,000 people gathered in Warsaw on Sunday to show support for Poland’s EU membership. Among them was Donald Tusk, the former president of the European Council until 2019 and now leader of Poland’s opposition Civic Platform Party.

“What is it that brought us all here today? A pseudo-Court of Justice, a group of masqueraders in judicial robes, by order of the party’s leader, in violation of the constitution, decided to take Poland out of the EU,” Tusk told the crowd gathered in the Polish capital.

The protests were triggered after judges in Poland’s highest court last week ruled that the national constitution had primacy over EU law.

Didier Reynders, the EU’s justice commissioner, threatened retaliation against Poland Monday.

“We are waiting now for new decisions of the (EU) Court of Justice about the situation in Poland — also possible daily financial sanctions,” he told reporters.

Reynders had indicated earlier that those sanctions could amount to over $1 million per day until Poland accepts the legal rulings of the bloc.

Polish Prime Minister Mateusz Morawiecki originally brought the case to Poland’s Constitutional Tribunal in March. He has refused to implement two rulings made in July by the EU’s Court of Justice, which accused the Polish government of political interference in the judiciary.

The prime minister has denied such interference and said Monday that Poland is not seeking an exit from the EU.

“This is a harmful myth, which the opposition uses for its own lack of ideas about Poland’s responsible place in Europe,” he said on Facebook.

Government supporters have staged counterprotests and say the government was right to challenge the EU.

“They appropriate rights that they do not have the right to appropriate, and they want to interfere more and more,” government supporter Zygmunt Miernik told The Associated Press.

So, how close is Poland to leaving the European Union?

“There is a big concern in many European capitals and in Brussels that the more pressure the European Union exerts on Poland, the more likely ‘Polexit’ becomes. And I think this is a pitfall,” Piotr Buras, a Warsaw-based analyst with the European Council on Foreign Relations, said in an interview with VOA.

“This threat of “Polexit” of Poland leaving the European Union is overblown. Poland is a country where more than 80% of the population is in favor of EU membership. Poland is very much dependent on the internal market and also on the EU funds, including the (COVID-19) recovery fund,” Buras added.

That COVID-19 recovery fund is worth $66 billion. The EU has threatened to withhold the money unless Poland implements the changes to its judicial system.

Poland and some other member states, including Hungary, have repeatedly clashed with the EU over the rule of law, media freedom and minority rights.

“The battle we have now is basically about will the European Union allow this to happen, that populist, autocratic governments disregard the European standards and European laws, leading to an erosion of the EU foundations,” Buras said.

Those foundations have been shaken by the Polish ruling. European officials say the bloc must stand by its core principles, but so far, the Polish government shows little sign of changing course.