But a surge of sympathy could bring a reprieve for his political movement rooted in traditional Catholic values and a suspicion of Poland's big neighbors — especially if his identical twin brother Jaroslaw, once his partner as child actors and the key political operator in the political duo, runs for the presidency in his place.
Jaroslaw Kaczynski, 60, has not yet said if he will seek the job: for now he appears overwhelmed by grief at the loss of his brother in Saturday's crash that also killed 95 others, many from the Kaczynski brothers' inner circle.
"This is a time of mourning," Mariusz Blaszczak, a spokesman for Kaczynskis' Law and Justice, party told The Associated Press. "It's a bad time for any speculation."
The scenario of a run by Jaroslaw, however, would seem natural because with the president dead, there is nobody with as high a profile within Law and Justice — the party the brothers founded together — to represent it in the presidential race. The balloting was originally set for the autumn but now must be held by late June.
"If he decides to run, he may hope for a win on sympathy votes because Poles make decisions based on emotions," said Kazimierz Kik, a political scientist at Kielce University.
Lech Kaczynski and the Law and Justice party saw their popularity decline sharply over the past three years. Many Poles grew tired of the polarizing role the Kaczynski camp played in seeking to punish old communists and in their skepticism toward old foes Germany and Russia, and even the EU.
Their nationalist and socially conservative stance often put them at loggerheads with more liberal-minded leaders within the EU and in Germany, the country's biggest neighbor.
In 2007, Law and Justice was defeated in parliamentary elections in a clear signal that many Poles had tired of the brothers' divisive style. Jaroslaw lost the job of prime minister he had held for nearly a year and a half — with his brother as president in a largely ceremonial role. Poland's president is commander in chief but the role carries more symbolic weight than real power.
Since then, support has remained high for the rival Civic Platform party, a centrist grouping led by Prime Minister Donald Tusk. Many — especially younger Poles and the rising entrepreneurial classes — like the party's no-drama pragmatism and support for free-market economics.
Tusk, whose job makes him Poland's most powerful leader, was not on board the plane. Nor was the country's most famous son, Solidarity founder and ex-President Lech Walesa.
But the tragedy claimed many other elites, including several military commanders, a former president-in-exile and Anna Walentynowicz, the woman whose dismissal from the famed Gdansk shipyard sparked a labor uprising that ultimately toppled communism.
The nation will have to wait days, or possibly weeks, to learn who Law and Justice will put up for president. The other party member who is considered a possible contender, Zbigniew Ziobro, told the AP Monday that the grief is too great for thoughts of political posturing.
"It's a time for reflection and coming to terms with this pain that we're all plunged in. I've lost colleagues whom I knew in everyday work and everyday life," Ziobro said.
It is far from certain that the outpouring of sympathy for the Kaczynski family — seen in the huge numbers that turned out in Warsaw to see the fallen leader's hearse travel to the presidential palace — would translate into ballot-box support.
"Jaroslaw Kaczynski was the prime minister once and he lost the trust of Poles," said Adam Mikolajczyk, 20. "I would not vote for him."
The main contender remains Civic Platform's Bronislaw Komorowski, the parliament speaker whom the constitution has thrust into the role of acting president by Kaczynski's death. His popularity was already high and he could also get a boost in the race thanks to his provisional presidential duties — a job he has so far carried out with reassuring solemnity.
"Jaroslaw Kaczynski should absolutely not run for the presidency. I realize it's a family tragedy but the country should be governed by a person who is not so bitter like both of Kaczynski brothers were," said Janusz Kislak, 58, a flower vendor.
Whether Jaroslaw runs may also hinge on the health of the twins' mother, Jadwiga, who has been hospitalized with lung and heart ailments in past weeks. President Kaczynski canceled at least one foreign visit lately to be by her side.
"The main question is whether Jaroslaw will be strong enough to overcome his personal tragedy and whether no new tragedy hits him," Kik said.
The crash also killed another presidential candidate, Jerzy Szmajdzinski, 58, a left-wing lawmaker and former defense minister who was to have represented the Democratic Left Alliance. That party, the democratic successor to the communist party, is generally out of favor in Poland.
The identical twins first entered the spotlight as child actors playing a pair of rascals in a movie based on a popular Polish children's book, "The Two Who Stole the Moon." As adults they joined Walesa's anti-communist struggle and in democratic times waged a fight against a system that allowed many former communists to continue to wield power and enjoy wealth.
They avoided appearing in public together but did join together for cameras when Pope Benedict XVI visited Poland in 2006, a treasured moment for the devoutly Catholic twins.
Jaroslaw was given the news of his brother's death by Foreign Minister Radek Sikorski, who was the first leader in Poland to be informed of the tragedy.
"I had to tell him something which I knew would be awful," Sikorski said Monday in an interview on Radio TOK FM. He said Jaroslaw reacted calmly. "But at the same time I could sense the emotion on the other side."
Associated Press Writers Monika Scislowska and Marta Kucharska contributed to this report.