Tusk, a former top European Union official, convened with his future ministerial team at the houses of parliament in Warsaw on Friday, Polish state news agency PAP reported.
The liberal politician said afterwards that his new government would begin by "restoring the rule of law" in Poland.
Image: Polska Agencja Prasowa (PAP)
Tusk, who leads the liberal Civic Coalition (KO) group, said that, during its eight years in office, the outgoing conservative Law and Justice (PiS) party "sidestepped or simply violated" the Polish constitution and European law.
He added that, under his new Cabinet, Poland would join the EU's European Public Prosecutor's Office (EPPO), seek to resolve a protest by Polish haulers at the border with Ukraine, and "carry out an audit" of the previous government's policies and personnel decisions.
Tusk said that the outgoing conservative government had channeled public funds to party officials in recent days, including some PLN 500 million (EUR 115 million) from the culture ministry, the PAP news agency reported.
Tusk's Civic Coalition is poised to take power in Poland, forming a coalition government with the centre-right Third Way alliance and the Left, after an election in October.
New PM for Poland on Monday?
Mateusz Morawiecki, Poland's head of government since 2017, was reappointed prime minister by President Andrzej Duda in November, but his conservative Law and Justice (PiS) party lacks a majority in the new parliament.
If Morawiecki's Cabinet fails to secure a vote of confidence from MPs on Monday, the lower house, the Sejm, will appoint another prime minister.
A bloc of opposition parties has put forward Tusk as their candidate for prime minister.
At 4:30 p.m. on Monday, the lower house will launch the procedure to elect a new head of government, including a floor debate and a vote at 8 p.m., according to a schedule released by the Sejm Office.
On the following day, the new prime minister will address MPs at 9 a.m., outlining his planned policies and the proposed team of ministers, and ask the house for a vote of confidence in his Cabinet, the PAP news agency reported.
That vote is scheduled for 3 p.m. on Tuesday, December 12.
Tusk's Cabinet is then expected to be sworn in by the president on December 13.
Tusk on Friday urged the head of state to appoint his government on December 13, in time for a crucial summit of EU leaders, starting in Brussels the next day.
He said the summit would make decisions "of great importance to Poland's interests."
Tusk was Poland's prime minister from 2007 to 2014 before becoming president of the European Council, a role he held until 2019.
Source: PAP/pap.pl, RMF FM