Poland's leaders, including acting President Bronislaw Komorowski (left) have a delicate task leading up to the election
By Adam Easton
BBC News, Warsaw
The plane crash which killed the Polish president, Lech Kaczynski, and dozens of senior public figures will have a major impact on Poland's political scene.
The most obvious result is that it triggers early presidential elections, which must be held before the end of June.
They were scheduled to take place in October - and although Mr Kaczynski had not publicly announced he would run for a second term, it was widely assumed he would.
The former president's twin, Jaroslaw - himself a former prime minister - leads the country's main opposition party, Law and Justice, and Lech was its natural candidate despite the fact that opinion polls consistently showed he would lose.
The plane crash did not only kill the president, it touched all the main political parties - but it had the largest impact on the Law and Justice political camp.
It has not caused a power vacuum, however. In Poland executive power lies with the government. Under the constitution, the 57-year-old Speaker of the lower house of parliament, Bronislaw Komorowski, is now acting president and it is his task to announce the date of the elections.
Jaroslaw Kaczynski has not said if he will run in his brother's place
Those elections may be influenced by the unprecedented scale of the disaster. The profoundly shocking manner in which it occurred has heightened Poles' sense of grieving, and caused a national outpouring of sympathy for the victims and their families.
Jacek Zakowski, a leading columnist for Polityka magazine, is not so sure, however, that this sympathy will translate into votes for the opposition party.
"I think what people are expressing right now is deep sorrow concerning not only the president and his wife but for the entire tragedy. Every Pole can find someone on that plane he likes. To try to convert this into political gain would be a risky game and could provoke people's anger," he says.
It is not clear whom Law and Justice will appoint as its presidential candidate, although at least one of its MPs has said Jaroslaw should run on a platform of continuing his brother's work in office.
Deep in grief, 60-year-old Jaroslaw Kaczynski has not made any public comments about his party's plans.
Whomever the party chooses will come up against Mr Komorowski, who is the governing party, Civic Platform's candidate.
The tragedy has united the nation in mourning
That means Mr Komorowski has the delicate task of leading the nation through the period of national mourning and announcing the date for elections he hopes to win.
According to many polls published before the tragedy Mr Komorowski, who has been endorsed by Lech Walesa, Poland's legendary anti-communist activist and former leader of the Solidarity movement, was likely to be the winner of the elections.
A former defence minister, Mr Komorowski, is the son of a count and is distantly related to Princess Mathilde of Belgium.
A father of five, he met his wife, Anna, through the Scouts, which remains a major youth movement in Poland.
During the communist era he was an opposition activist, publishing an underground magazine, and he was interned when the authorities introduced martial law in 1981.
For most analysts Mr Komorowski remains the favourite to cement his position as president.
Both the Law and Justice Party and the main left-wing party, the SLD, lost their candidates to the tragedy.
Cracks in unity
It will be a short campaign and one influenced, at least initially, by the solemn mood in the nation, which has provoked political unity unseen since the death of the Polish Pope, John Paul II, five years ago.
However, the first cracks have already appeared over the family's decision to bury Mr Kaczynski and his wife in Poland's national shrine, Wawel Cathedral in Krakow.
Hundreds of demonstrators took to the streets of Krakow on Tuesday night, some holding banners saying the late president should not be buried alongside the nation's kings, saints, national heroes such as Tadeusz Kosciuszko and the father of Poland's modern independence, Marshall Jozef Pilsudski, and the Polish bard, Adam Mickiewicz.
In a front page commentary on Wednesday, leading daily, Gazeta Wyborcza, called the family's decision "hasty and emotional", adding the natural location for the couple's burial would be in Warsaw alongside previous presidents in either the city's cathedral or Powazki cemetery.
Some commentators believe the decision could backfire on Jaroslaw Kaczynski if he does decide to run for president.