Poland’s ruling conservatives should take a step back in their attempted reform of the country’s top court, European Council President Donald Tusk said on Saturday as the country suffers its worst constitutional crisis in decades.


Tusk’s comments marked a rare intervention in Poland’s domestic politics. He resigned as Polish prime minister in 2014 to take up the job in Brussels and has largely shied away from local affairs since then.


In October 2015, his centrist Civic Platform (PO) party lost a parliamentary election to the eurosceptic Law and Justice (PiS) party — led by Tusk’s political arch-rival Jaroslaw Kaczynski, which now forms a majority government.


Since coming to power, the Law and Justice party has scrapped the previous parliament’s nominations to the constitutional court, and amended the legislation which regulates its proceedings. Critics say that if implemented, the changes would make it impossible for the court to review and rule on new legislation.


“I have no doubt, and this isn’t just my opinion, that it’s the government who should take a step here, and it should be a step back,” Tusk said, commenting on the crisis to Polish media during his visit to Arlington, Virginia.


“This means that the government should back out of the unnecessary — in my view — actions toward the constitutional court,” he added.


The opposition says the attempted reform violates the constitution, and the court itself struck it down as illegal, but the party refuses to recognize the ruling, effectively putting the changes in legal limbo.


Thousands of people have protested against the reform at opposition rallies, demanding the government respect the court’s verdict.


The months-old cabinet also faces growing international pressure over the issue, after the EU Commission launched an unprecedented rule of law procedure against Warsaw. Poland’s closest ally, the United States, has also expressed concern.


Polish Prime Minister Beata Szydlo said she was “a little disappointed” by Tusk’s remarks.


“It seems to me that he had a chance to … ease this unjustified row around Poland,” she told private broadcaster Polsat News. “Tusk, as a high-ranking European politician should aim at that.”