Only if there is a firm alternative to the government will the Socialists vote for or present a rejection motion, he added.


Carlos César spoke to journalists after a meeting with the minister for parliamentary affairs, Carlos Costa Neves, said he was using "prudent and responsible" language on the possibility of the three left-of-centre parties reaching a deal.


"So long as there is no accord signed with the PCP and Left Bloc, it's nor worth assessing the state of the negotiations as being at 90 or at 40 percent," he said.


"When there is that accord, it should be announced and it's important that this accord is cleared up, evidently, before the debate on the government programme," he said, noting that the Socialist Party had made a commitment not to vote against the government unless there was an alternative in place.


"We shall only constitute a political force that contributes to bringing down the government... if we are simultaneously bearers of a responsible, stable alternative, with a lasting sense that offers the Portuguese a feeling of tranquillity and confidence."


The party will not, he reiterated, vote for nor present any rejection motion unless it has at the same time "the guarantee that we have an agreed and solid alternative with the remaining political parties."


In his answers to journalists, César indicated that there is alo no agreement at present on a joint rejection motion, and indeed that separate motions are more likely.


On a broader agreement for government, he said that "it is presumed that it has a high probability" of being achieved.