Mr Di Rupo repeated that he did not wish fresh elections. He insisted that he wanted the Flemish nationalists, who favour the break up of Belgium, to enter the federal cabinet. He stressed that he would do everything in his power to reach agreement with the nationalists.
The Francophone socialist leader refused to speculate about a tripartite government uniting the country's three historical political traditions.
Mr Di Rupo denied that he had had a secret meeting with Flemish nationalist leader Bart De Wever on Tuesday. "It wasn't secret" he told reporters: "A solution is only possible if the two largest parties talk."
The PS leader believes that sufficient elements are present to allow an agreement: "Everybody must now take a step."