Italian Prime Minister Romano Prodi has been asked by the president to remain in office after resigning last week over a key vote on foreign policy.
The issue of troop deployments split Mr Prodi's coalition
Seeking to end the crisis, President Giorgio Napolitano said Mr Prodi should stay but seek a vote of confidence in his young, centre-left government.
He dismissed as pointless the idea of fresh elections, as demanded by former prime minister Silvio Berlusconi.
Mr Prodi resigned on Wednesday after losing a vote on troops in Afghanistan.
But his left-wing coalition partners subsequently signed up to a 12-point deal endorsing him in his role.
Despite the deal, any coalition which operates with the support of Communists and both moderate and radical left-wingers will remain relatively shaky, correspondents say.
'Sleep on it'
Mr Prodi's government had been forced onto the defensive over the continued deployment of 2,000 Italian troops in Afghanistan, with strong opposition from some of his more left-wing coalition partners.
Plans for the expansion of a big US military base in Vicenza, northern Italy, had also sparked protests both within his government and on the street.
The government was brought down by two Communist senators who rebelled against their own parties and joined the opposition in a key vote on Wednesday.
The motion had asked the Senate to approve the government's foreign policy.
Although it was not a formal confidence vote, Foreign Minister Massimo D'Alema had urged the government to resign if it could not win the Senate's backing.
After announcing his resignation, Mr Prodi secured the renewed backing of leaders of his coalition partners in a late-night deal on Thursday. He had apparently persuaded at least one extra senator to support him after intense negotiations.
Correspondents say it was the prospect of Mr Berlusconi potentially returning to power which provided impetus to the talks.
"I will present myself before the parliament as soon as possible to seek its confidence," Mr Prodi said after the president's announcement on Saturday.
The vote in the lower house and the Senate is expected to be held on two separate days, probably starting on Wednesday.
Even if he wins the vote, the BBC's Mark Duff says that if Mr Prodi is to have any real chance of survival he needs to broaden the base of his coalition to break his dependence on some of its more unreliable - and radical - members.