Il Nuovo Postiglione - Pro-Trump nationalist to take over as Poland's new president

Nationalist historian Karol Nawrocki, a political novice, will be inaugurated after winning a June 1 election in a major blow for Prime Minister Donald Tusk, a former European Council president.

Rallies of support for the new president are expected in Warsaw as Nawrocki begins his five-year mandate with a speech to parliament.

Nawrocki, who sought US President Donald Trump's backing during the campaign, is set to take the oath of office and give a speech to parliament at around 0800 GMT.

His narrow victory against liberal candidate Rafal Trzaskowski confirmed the high degree of political polarisation in the EU and NATO member state, a key supporter of neighbouring Ukraine.

Presidents in Poland can initiate as well as veto legislation, and have some influence over the country's foreign and defence policies.

The outgoing president, Andrzej Duda, had already been at loggerheads with Tusk over many issues, including opposing easing an almost total ban on abortion.

- 'Annoy us' -

But relations are likely to be even worse under Nawrocki as the political climate heats up ahead of parliamentary elections planned for 2027, analysts say.

"I have no doubt that Mr Nawrocki will do everything to annoy us," said Tusk, who warned that he would not let Nawrocki "demolish" his government.

Nawrocki has repeatedly branded Tusk's government as "the worst in the history" of democratic Poland.

He has promised to be "an active president" from the start and has said he wants to "stimulate" the government with various bills.

In a video posted on social media on Tuesday, he said his inauguration would open "a new chapter in the history of our beloved Poland".

"Let us unite," he said.

The government holds a parliamentary majority but government and president may be forced to make some compromises.

"Both parties should realise that engaging in intense confrontation is obviously not the way forward," said Piotr Trudnowski, a member of Klub Jagiellonski, a Christian-Democrat think tank.

- 'Poland First, Poles First' -

Ewa Marciniak, a political scientist at the University of Warsaw, said that Nawrocki would have to work with the government on foreign policy -- in which he has "no experience".

During the election campaign, he highlighted the importance of ties with the United States and his close ties with Trump.

"It is precisely from this that he will build his foreign policy, at least initially," Marciniak said.

One major difference could be relations with Ukraine.

Trudnowski said Nawrocki would "not be as enthusiastic" as his predecessor on Ukraine.

During his campaign, Nawrocki opposed the idea of NATO membership for Ukraine and criticised Kyiv for not having "shown gratitude for what the Poles have done".

Under his slogan "Poland First, Poles First", he was critical of some of the benefits received by the more than one million Ukrainians who have fled to the country.

Ukrainian President Volodymyr Zelensky has congratulated Nawrocki and emphasised the importance of close ties with Poland -- a vital transit country for military and humanitarian supplies to his country as it fights off Russia's invasion.

After speaking to Nawrocki by phone last week, Zelensky said the two had agreed to visit each other and seek forms of cooperation "that will bring real results for both our countries and our people".

Zelensky said he was "thankful for the readiness to work together and for the assurance of continued support for Ukraine".

A.Ferrara--INP