The reshuffling came after weeks of speculation that Prime Minister Beata Szydlo might be replaced, even though her government is popular with many Poles and the economy is booming.
Szydlo resigned during a meeting of the ruling Law and Justice party in Warsaw, party spokeswoman Beata Mazurek said. The party leadership wants Szydlo to serve in another senior government position, Mazurek said without elaborating.
Deputy Foreign Minister Jan Dziedziczak suggested Szydlo will be the deputy prime minister, a post Morawiecki held in her government.
Government critics interpreted the leadership change as primarily an attempt to divert attention from a vote scheduled for Friday on laws that would give the ruling party significant power over Poland's judicial system.
Party leader Jaroslaw Kaczynski is widely seen as the real power behind the government, and it's not clear if Morawiecki will seek to set an independent course or if he would also largely follow the direction Kaczynski sets, as Szydlo did.
Some analysts think Kaczynski wanted Szydlo to step down because she was unable to manage government infighting. They said Kaczynski respects Morawiecki, a party newcomer, but does not see him as a threat.
The state news agency PAP reported that lawmakers will vote Tuesday on Morawiecki and his Cabinet. Approval is expected given the ruling party's majority in parliament.
While Szydlo's 2-year-old government is riding high in opinion polls, Morawiecki has overseen its economic development. Poland now enjoys record low unemployment of around 7 percent, growing wages and growth of over 4 percent per year.
Still, the country's international image has suffered dramatically since Law and Justice assumed power, mostly over new laws that have eroded the independence of the judicial branch.
The government also drew criticism from abroad following an Independence Day march last month that was organized by far-right groups. It drew an estimated 60,000 participants, including some who carried banners and signs with white supremacist messages.
Some government members praised the march. The interior minister called it a "beautiful sight," although Poland's president denounced it unequivocally.
Some see Morawiecki, a former international banker who speaks foreign languages, as better placed than Szydlo to defend the country in dealings with European partners who believe democracy is eroding in Poland.
He is expected to reassure financial markets, given that he is regarded as business friendly, especially by the standards of the others in the Law and Justice party.
Szydlo, a coal miner's daughter and the mother of a priest, has wide support among conservatives. Many party supporters said in recent days they didn't want her to resign.
She thanked her supporters in a tweet Thursday night.
"These two years were an amazing time for me, and serving Poland and Poles an honor," she wrote.
Earlier Thursday, Szydlo and her Cabinet easily survived a no-confidence vote in parliament called by the opposition centrist Civic Platform party, which accuses the government of harming Poland with laws that it says are anti-democratic.
Two bills are set for a final vote in parliament Friday that would give the government greater control of the judicial system. The bills have been criticized by the European Union and others as an anti-democratic threat to Poland's rule of law.
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