By Nick Thorpe
BBC correspondent in Skopje
The small pile of flowers laid by well-wishers in front of the presidential building in Skopje is growing hour by hour.
A sudden thunderstorm - the same bad weather which may have caused the president's plane to crash on Thursday morning in Bosnia-Hercegovina - sends the mourners hurrying for cover.
Macedonians have paid tribute outside parliament
But soon the sun shines again, and the thin yellow Orthodox candles are relit.
"This is a tragedy of cosmic proportions for Macedonia," said Biljana Goceva, a professor of philosophy at the main university in Skopje, one of those laying flowers.
A rain-soaked message, signed Harun Alili - an ethnic Albanian name - read: "May his dream of a free, modern Macedonia, integrated with Europe, survive.
"May he rest in peace."
In a café across the River Vardar in the old quarter of the city, the owner preferred not to give his name - inter-ethnic relations in this city are still tense.
He said people would only realise what a good president Boris Trajkovski had been, now that he was gone.
Under the Macedonian Constitution, the Speaker of Parliament, Lyupco Jordanovski, will now become acting president.
He must call a new presidential election within 40 days of the president's death - most probably in early April.
Presidential elections were due anyway this November, and Mr Trajkovski had been widely expected to stand and win again, even though his former party, the nationalist VMRO, was uncertain whether to back him.
Inter-ethnic relations are still tense, two years after the conflict ended
The ruling Socialist Democrats also have no obvious candidate, so a fierce battle can be expected within the main parties to select their candidates.
A commentary in the Albanian-language daily Fakti on Friday also suggested strong arguments among ethnic Albanians over which Macedonian candidate to vote for.
Boris Trajkovski was elected largely thanks to key Albanian support in November 1999.
In August 2001, the Ohrid peace agreement ended seven months of conflict, in which the NLA ethnic Albanian rebels fought the Macedonian police and armed forces.
A new constitution was approved in December 2001, which established Albanian as an official language, alongside Macedonian.
Elections in September 2002 brought a new government to power, a coalition of the Social Democrats led by Prime Minister Branko Crvenkoski and the Democratic Union for Integration, or DUI, led by former rebel chief Ali Ahmeti.
The government has been gradually implementing the terms of Ohrid, under the eagle eyes of Nato, EU monitors, police, and the Organisation for Security and Co-operation in Europe.
Some clear progress has been recorded. One thousand new Albanian police officers have been given jobs, though they still constitute under 10% of the force.
Ethnic Albanians are estimated to make up about 30% of the population.
But serious problems remain. A 2003 study by the United Nations Development Program showed the population deeply divided over the Ohrid peace agreement, with more than half Macedonians opposing its provisions, while Albanians largely support it.
Most Macedonians feel it was imposed on their country from abroad.
There are many delicate areas.
Macedonians fear that any decentralisation of the country increases the danger of ethnic Albanians building autonomy which could help them break Macedonia apart in the future.
At the same time, Macedonians accuse ethnic Albanians of showing little loyalty to the Republic of Macedonia.
Another sensitive area is education. Albanians traditionally have lower qualifications, and there have been complaints that some of the new recruits to the police are not of a high enough standard.
Years will clearly be necessary for the implementation of all the promised reforms, and the economic crisis exacerbates ethnic tensions.
As state firms go bankrupt or are privatised, all workers suffer equally.
But the Ohrid agreement calls for a higher proportion of Albanians to be given jobs.
Macedonians now feel they are being discriminated against in the job market.
The immediate task, if the president's death is confirmed as feared, is to bury and mourn the him and the other eight people on his plane.
"Boris Trajkovski was above all a decent man," said Saso Ordanovski, a Macedonian journalist who knew him well.
"He was not corrupt, which is rare among politicians - not only in the Balkans.
"And he knew how to listen."