“I will be indebted to all those who trusted in this new, wonderful Poland, to all those who trusted us … and decided to make this historic change,” he told the chamber after the vote on Monday.

Earlier in the day former prime minister Mateusz Morawiecki of the nationalist Law and Justice (PiS) party lost a vote of confidence.

His party came first in the October 15 election and got the first shot at forming a government, but it lacked necessary majority and all other parties had ruled out working with it.

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PiS has cast itself as a defender of Poland’s sovereignty and identity that has also improved living standards for millions by boosting social benefits and the minimum wage.

Critics, however, say PiS undermined judicial independence, turned state-owned media into a propaganda outlet and fomented prejudice against minorities such as immigrants and the LGBT community.

In a sign of the deep personal animosity PiS leader Jaroslaw Kaczynski feels towards Tusk, he stormed onto the podium following the vote and told the new prime minister – “I know one thing, you are a German agent!”

During the election campaign PiS regularly painted Tusk as Berlin’s stooge.

Tusk was to give a speech to parliament on Tuesday laying out his government’s plans and will then face a vote of confidence.

While the mood among Tusk supporters in parliament and beyond was jubilant, events elsewhere in Warsaw highlighted the challenges he will face in unblocking the frozen EU cash.

Poland’s Constitutional Tribunal ruled on Monday that judicial reform legislation which Poland needed to pass in order to access the funds was unconstitutional.

It reached the same conclusion about penalties imposed by the European Union’s top court before it reaches a final ruling, known as interim measures.

While Tusk is seen in Brussels as a leader who can set the bloc’s largest eastern member back on a pro-EU course, officials have said that no funds will be released without judicial reforms.

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Analysts say this task could be complicated not only by the presence of judges appointed under an overhaul implemented by PiS which critics say politicised the courts, but also by the veto power of President Andrzej Duda, a PiS ally.

Nevertheless, congratulations poured in from abroad, including from Ukrainian President Volodymyr Zelensky and European Commission President Ursula von der Leyen.

“Your experience and strong commitment to our European values will be precious in forging a stronger Europe, for the benefit of the Polish people,” she wrote on social media platform X.

Poland’s October election saw a record turnout of 74 per cent with people in some locations queuing for hours to vote.

“They didn’t give up in these lines, they just stayed there until midnight and they still wanted to be part of this change,” parliament speaker Szymon Holownia told reporters.

“Dear members of parliament … the power that we showed on October 15 is in our hands.”

There has been huge interest in the parliament’s workings since the election and subscriptions to its YouTube channel have rocketed.

Certain sessions have attracted well over a million viewers on the platform and one Warsaw cinema showed Monday’s session on the big screen, attracting so much interest that around 2,000 people were on a waiting list for tickets.

Some observers have also attributed the surge in interest in part to the appointment of Holownia as speaker. His wisecracking while running debates has charmed many who first got to know him as a host of a prime-time talent show.

Lech Walesa, Poland’s first democratically elected president after the fall of communism, who led the Solidarity trade union and won the Nobel Peace Prize, was in attendance and received multiple standing ovations from the coalition set to take power.

Dressed in a jumper bearing the word “Constitution”, which opponents of PiS wear to show their condemnation of what they say was democratic backsliding under the party’s rule, Walesa, 80, had just left hospital after a bout of Covid-19 to attend.