The Francophone socialist leader will resume his efforts on Saturday. In the meantime the king will consult party leaders.
Mr Di Rupo's efforts will focus on greater autonmy and financial responsibility for the regions and communities and the strengthening of the federal state.
The Francophone socialist leader has been holding talks for six weeks now. In a report handed to King Albert on Wednesday he spoke of significant progress.
Speaking at a news conference after his meeting with the monarch Mr Di Rupo explained that he had accepted the task out of a sense of statesmanship and because he hoped to achieve progress soon.