WARSAW, Poland (AP) — The U.S. ambassador to Poland announced on Thursday that the United States will have “no further dealings, contacts, or communications” with Włodzimierz Czarzasty, the speaker of the lower house of the Polish parliament, over what Rose called “outrageous and unprovoked insults directed against President Trump.”

Amb. Tom Rose did not specify what those alleged insults were, but Czarzasty had issued a public statement on Monday in which he said he would not support an initiative of his Israeli and American counterparts to nominate U.S. President Donald Trump for the Nobel Peace Prize.

Czarzasty is one of the leaders of a left-wing party in the liberal government led by Donald Tusk.

Ever since Trump came to power, Poland has had to walk a fine line between defending its European allies while not upsetting its most powerful ally, the United States, on which peace in neighboring Ukraine depends. Warsaw has so far managed to do this by having Tusk handle European Union matters and letting President Karol Nawrocki, who came to power supported by the national-conservative opposition party Law and Justice, connect with Trump.

Nawrocki enjoys good relationships with Trump, who endorsed him during the electoral campaign for presidency last year, and invited him to the White House soon after the Pole took office. As the two presidents sat side by side in September in the White House, Trump declared he does not intend to pull U.S. troops out of Poland, a sign of support for the new president and his aims. “We’ll put more there if they want,” Trump even said.

Yet this week’s dispute highlights the difficulty of Poland’s position in the current international context.

Czarzasty did not mince his words on Monday when he said Trump “does not deserve the Nobel Peace Prize.” He said Trump “represents power politics and, by the use of force, pursues transactional politics.” This often means “breaking international law,” the Polish politician added.

He criticized Trump for not recognizing enough the role Polish soldiers played in U.S. military missions and for “the instrumental treatment of other territories,” such as Greenland.

Polish Prime Minister Donald Tusk was quick to respond to Rose’s announcement.

“Mr. Ambassador Rose, allies should respect, not lecture, each other,” Tusk wrote on X Thursday afternoon.

Rose, however, was undeterred. He replied to Tusk that, despite the Polish prime minister himself being “a model ally and great friend of the United States,” Czarzasty’s comments “were so potentially damaging to your government.”

Insulting Trump, “the greatest friend Poland has ever had in the White House,” was “the last thing” a Polish leader should do, Rose warned.

Earlier this week, Nawrocki called a meeting of a national security body to discuss, among others, whether Poland should join Trump’s Board of Peace as well as to clarify alleged “eastern business and social contacts” of Czarzasty. The parliament speaker denies any nefarious relationships in Russia or Belarus.

Law and Justice, the main opposition party in Poland who supported Nawrocki’s presidential bid, is hoping to regain power in parliamentary elections next year. Weakening Tusk’s coalition partners is part of its strategy.

Czarzasty himself said on Thursday night that, despite respecting the U.S. as a key ally for Poland, he would not change his position.

The U.S. State Department did not immediately respond to a request to comment.