Italy's former justice minister, who resigned over a corruption probe, has withdrawn his party from Prime Minister Romano Prodi's governing coalition.
Mr Mastella says the charges are part of a witch-hunt against him
Clemente Mastella's centrist party has three seats in the Senate, while Mr Prodi's coalition government has a majority of one in the upper house.
Mr Mastella told a news conference he would continue to support the coalition only on a case-by-case basis.
He and his wife are under investigation for corruption, which they deny.
Mr Prodi said he hoped the former minister would resume his post after dealing with the courts.
Mr Prodi, who initially rejected Mr Mastella's resignation, also told parliament that he would be acting as interim justice minister.
Speaking on Thursday, Mr Mastella said his Udeur party would continue to support the government but would "not accept compromises as we have until now".
The 60-year-old resigned on Wednesday after his wife was put under house arrest. It was revealed later that day that Mr Mastella was also under investigation.
Mr Mastella and his wife, Sandra Lonardo, who leads the council in Italy's Campania region, both deny any wrongdoing.
Mr Mastella said the inquiry was part of a witch-hunt against him.
Prosecutors are looking into allegations of a corrupt hospital appointment at a state hospital in Caserta near Naples.
Neither Mr Mastella nor his party have commented on his own involvement in the inquiry.