It was just minutes after Donald Tusk made his triumphant return as Poland’s leader that his archenemy stepped to the podium in Parliament to rain acid on his parade.
“I don’t know who your grandfathers were but I know one thing: You are a German agent, just a German agent,” growled Jaroslaw Kaczynski, the chairman of Law and Justice, the right-wing party that, until Monday, had held all the reins of power.
The accusation, one of many smears aimed at Mr. Tusk over a political career stretching back to the 1980s, came after Parliament endorsed Mr. Tusk as prime minister, stirring joy and relief among Polish liberals and pro-European centrists.
The attack reflected the no-holds-barred approach to Polish politics after eight years of Law and Justice rule. But it also highlighted the difficulties for many in Poland of pinning down who their country’s next leader is and where he stands.
In a country that has been largely mono-ethnic and monolingual since the end of World War II, Mr. Tusk stands out as a man of eclectic identities, interests and linguistic talents.
As Parliament on Tuesday debated whether to endorse a cabinet proposed by Mr. Tusk, one of his most strident critics, the far-right legislator Grzegorz Braun, used a fire extinguisher to put out Hanukkah candles during an event with members of the Jewish community.
The new government lineup later won a vote of confidence as expected.
Mr. Tusk has described himself as having four parallel identities: a proud son of Gdansk, the formerly German port city of Danzig on the Baltic Sea; a Kashubian, an ethnic minority native to northern Poland with its own language and traditions; a Pole and a European.
He speaks Polish, Kashubian, German and English, a language he barely knew when he took a break from Polish politics in 2014, to take a senior job in Brussels, but mastered quickly.
Being Polish, Mr. Tusk said in 2014, when he became president of the European Council is “my main identity” but the others matter, too — a position that baffles Mr. Kaczynski and other Polish nationalists, who see allegiance to the Polish state as indivisible.
Riina Kionka, a diplomat from Estonia who advised Mr. Tusk in Brussels, remembers him as both a “passionate European” and a “proud Pole determined to lead his country.”
Mr. Tusk always had “his two feet firmly on the ground” and sought compromise rather than total victory, she said. “He always told us: ‘It is better to have part of something than all of nothing.’”
This distaste for all-or-nothing dogmatism led some to question the convictions of a politician who began his career in a circle of radical free-market believers but who, in Poland’s recent campaign, promised to preserve a raft of welfare payments introduced by Law and Justice.
Asked in 2013 whether he had changed his earlier views, he quoted the philosopher Leszek Kolakowski, a former Marxist who, after leaving Poland, became a trenchant critic of communism and described himself as a “liberal conservative socialist.” That, Mr. Tusk said, described his own views.
“He is a political cherry picker,” said Jarolaw Kuisz, the author of a recent book, “The New Politics of Poland.” He added, “He takes what he sees as the best bits from every part of the spectrum.”
Active in politics for more than 40 years, Mr. Tusk started out as a youth activist and journalist with Solidarity in Gdansk. After communism’s collapse, he went on to win two consecutive terms as prime minister, though he cut short the second to take the Brussels position.
The job that perhaps prepared him best for his current role, juggling implacable hostility from Law and Justice and tensions within his diverse alliance of supporters, however, was one he took in the 1980s in Gdansk, after communist authorities imposed martial law.
Unable to find regular work after being briefly arrested, he took a job scaling chimneys and high buildings with mountaineering gear so as to paint or repair them.
This “high-altitude work,” Mr. Tusk later recalled, involved being a “crazy alpinist” and equipped him to calibrate results and risk, a useful political skill.
Wladyslaw Kosiniak-Kamysz, leader of the Polish Peasants Party and Mr. Tusk’s candidate for defense minister, praised him Monday for taking the risk of leaving Brussels to return to Polish politics in 2021, starting what seemed a long-shot effort to beat Law and Justice.
“He showed courage when he abandoned a comfortable life,” he said. “He abandoned lucrative posts and came back here.”
Mr. Tusk’s flexibility has alarmed some progressives. They loathe Law and Justice but complain that Mr. Tusk has not rallied more forcefully to their side on issues like abortion, on which the outgoing government imposed a near total ban and which Mr. Tusk did nothing to liberalize when he was prime minister.
Mr. Tusk declared women’s rights the “No. 1 issue” in Poland this year but, ahead of the general election, removed from his party’s list of candidates an activist who called for allowing for abortion at any stage of pregnancy, a position that risked alienating voters.
His party, Civic Coalition, wants to liberalize Poland’s harsh abortion law but only to allow termination up to the 12th week of pregnancy.
Zuzanna Dąbrowska, a veteran political journalist, said Mr. Tusk deserved credit for addressing an issue that most politicians avoided. “The majority in Poland has the same opinion that policy on abortion should be more liberal. But politicians have done everything to avoid this reality.”
To become prime minister, Mr. Tusk stitched together an array of diverse opposition parties that together won a clear majority of seats in Parliament, and joined forces on Monday to reject Law and Justice’s nominee as prime minister and select Mr. Tusk. They include a leftist grouping, the center-right Polish Peasants Party and hard-line free-market liberals.
“To be a good prime minister you must be everything but sometimes you can’t combine water and fire,” said Bartosz Rydlinski, a political scientist at Cardinal Stefan Wyszynski University in Warsaw. “You cannot have low taxes and an effective welfare state. This is Tusk’s biggest challenge.”
A fan of Miles Davis who studied history at university, Mr. Tusk has sometimes alienated potential voters, particularly more traditional-minded ones in small rural towns and villages.
Mr. Tusk offended millions of Poles in 2005 by dismissing conservatives as a “mohair coalition” — a reference to the berets many older women wear to church. Mr. Tusk apologized but struggled for years to shake off an image of haughty contempt.
He has since talked about his youth in what he describes as “poverty” in Gdansk, particularly after his father, a carpenter, died when he was 14, and how he used to hang out with street toughs. His older sister, he says, helped set him straight.
As a university student and then a journalist and youth activist with Solidarity, he embraced free-market economics. He helped found the Liberal Democratic Congress, a group of anti-communist free-marketeers. After the 1990 election of the Solidarity leader Lech Walesa as president, he was involved in managing the privatization of state assets.
Widespread public discontent with economic “shock therapy” crushed his early political ambitions. His party’s defeat in a 1993 election dampened his faith in free-market orthodoxy.
“He realized he had to follow political currents and adjust to reality,” said Ms. Dąbrowska. “He has been doing this ever since — adjusting his views and himself to political reality.”
After retreating from politics for four years to write books, he won a seat in the Polish senate and then helped set up Civic Platform, a liberal party. He became prime minister after the party won a 2007 election, and served a second time after another victory in 2011.
He boasted after his second triumph, “we have no one left to lose to” and, to the dismay of many supporters, decamped to Brussels before finishing his second term.
A year after his departure, Law and Justice defeated his party in a parliamentary election and won an upset in a presidential race. “He was arrogant and misjudged the situation,” said Mr. Kuisz.
But Law and Justice recently made the same mistake, misjudging Mr. Tusk’s ability to reach out to voters after seven years in Brussels.
“He was presented as a lofty liberal and came back unsure of his success but determined to fight,” said Mr. Kuisz. “From Brussels he was suddenly everywhere in small towns and villages doing basic grass-roots politics.”