Mr. Di Rupo, appearing in parliament Thursday to defend the austerity proposals, lightly scolded the unions.
Voters in Flanders worried about deficits can do nothing to sanction free-spending Mr Di Rupo.
Belgium's King Albert II and Prime Minister Elio Di Rupo met families of those killed and injured in the crash.
Mr Di Rupo will be Belgium's first French-speaking prime minister since 1974.
Since then, Belgium's French-speaking socialist party teamed up with five other parties to form a coalition government making Mr. Di Rupo prime minister.
Mr. Di Rupo's government has pledged to bring the deficit under the 3% limit next year and to balance the budget in 2015.
"This is a tragic day for the whole of Belgium, " Mr. Di Rupo said during a news conference in Sion, the capital of the canton of Valais.
Now a deal should be struck in time for the bow-tied Elio Di Rupo, leader of Belgium's Francophone Socialist party, to join other EU leaders at next week's summit.
On Belgian radio he accused Belgium's French-speaking PM, Elio Di Rupo, of "hiding behind the throne", arguing that he must have seen an advance copy of the speech and given it the green light.
The BBC's Maddy Savage in Brussels says he will now be looking to build on the party's success in local elections to take on Belgium's socialist Prime Minister Elio di Rupo in national elections in 2014.
The new Belgian government, led by Elio Di Rupo, a Socialist, was forced to cut cherished social programmes under threat of EU sanctions (a general strike forced leaders to fly in to this week's summit via a military airport).
应用推荐