Former Italian prime minister Romano Prodi is gathering support ahead of a vote of confidence this week that he must win to resume his position.
Mr Prodi resigned last week after suffering an embarrassing defeat over foreign policy in the upper house. But Italy's president asked him on Saturday to stay on as premier and put his majority to the test in parliament.
Mr Prodi needs to prove he has enough support in both chambers of parliament to keep his government afloat. The votes are expected to take place on Thursday and Friday.
Although his fractious broad coalition has a comfortable majority in the lower house, in the 315-seat Senate the bloc is effectively level with the opposition, forcing him to court outside senators for support.
But Mr Prodi appears to have won the backing of two extra senators, an independent and a Christian Democrat who served as deputy prime minister in Silvio Berlusconi's previous, centre-right government.
Barring defections, that raises his support to 158 elected senators, against 156 for the opposition. The Senate speaker, who is from Mr Prodi's bloc, traditionally does not take part in votes.
Mr Prodi is also relying on the votes of four of seven senators-for-life, unelected elderly statesmen and prominent figures on whom he has depended heavily since taking office in May after the closest election in Italy's post-war history.
Their support failed to offset a revolt by the left wing of his coalition in last Wednesday's Senate vote, but Mr Prodi's allies say this time there will be no upsets.
Commentators said Mr Prodi is likely to pass the tests, largely thanks to the centre left's fears that defeat would clear the way for the return of Mr Berlusconi, who wants an early election.