The current prime minister, Silvio Berlusconi, and his conservative coalition are refusing to admit defeat despite results that appear to give his rival Romano Prodi a slight majority in both houses of parliament.
Berlusconi has questioned the validity of the vote and asked for a recount on contested ballots.
However his hopes of victory faded further on Friday when the Interior Ministry reduced the number of such ballots from 80,000 to 5,200 - well below the number of votes needed to alter the result.
But Berlusconi, Italy's richest man, will not admit defeat before the results are made official, which will not happen until at least Tuesday.
Once the checks are completed, a top Italian court, the Court of Cassation, must certify the election result before the first meeting of the newly elected parliament, which is scheduled for April 28.
It was not clear when the confirmation would come. Court officials said Monday, a national holiday in Italy, that they were still missing reports from some electoral districts and did not know when the results of the final count would be announced.
It could still be weeks before Prodi is able to take office if he is confirmed as the winner.
The president must give the prime minister a mandate to govern, but incumbent Carlo Azeglio Ciampi's term ends in mid-May and has said he would leave the decision to his successor.
Berlusconi spent the Easter weekend in his mansion in Sardinia but has called for talks on "priority issues" facing the divided country, the ANSA news agency reported.
"Enough. It's time to work. I am working calmly for a future government and that's what we must do"
The 69-year-old said that failing such a dialogue, his center-right House of Freedoms coalition would have no choice but to "mount a hard and rigorous opposition, without benefit to anyone."
Prodi, a former president of the European Commission, has said this attitude stems from his rebuffal of Berlusconi's advances to form a grand coalition and said that he was already working on forming a new government.
"Enough. It's time to work. I am working calmly for a future government and that's what we must do," Prodi told reporters on Sunday.
His razor-thin margin of victory was just enough to win his disparate Olive Tree coalition a working majority in the 630-seat lower house of parliament. It also claimed a slim two-seat majority in the senate.
Italy's division between right and left was highlighted by Pope Benedict, who used his Easter Sunday address to urge the country's politicians to find a sense of unity.
"In the peculiar moment that Italy has been going through in recent months, may the Lord bring accord to the national community and strengthen in those who serve it the real desire to pursue common aims and genuine development for the good of all," he told pilgrims in St. Peter's Square.