Greek prime minister Antonis Samaras’ surprise offer to bring small opposition parties into the government in exchange for their support in this month’s presidential election did not appear to have persuaded enough independents to prevent a third voting round and possibly early elections.

A day ahead of the second voting round in parliament, only a handful of independent lawmakers had pledged to support the government’s candidate, the former European environment commissioner Stavros Dimas.

Greek media reported on Monday that Dimas could fall eleven votes short of the required supermajority in parliament on Tuesday.

Dimas failed to win election in a first voting round last week.

The left-right coalition government only has a five-seat majority in parliament and needs at least 25 lawmakers from the opposition to support its candidate.

The Communists, the far-left Syriza party and the fascist Golden Dawn, which command almost a third of the seats between them, have ruled out backing Dimas. That leaves the Democratic Left, which quit the government last year, and the right-wing Independent Greeks. Both had announced their intention to block Dimas before the first vote on Wednesday.

On Sunday, Samaras offered to bring the two smaller parties into the government and call new elections by the end of next year, rather than in 2016, in exchange for their votes. The Democratic Left and most Independent Greeks rejected the offer.

The Greek presidency is largely ceremonial but if parliament fails to elect a new head of state before New Year’s, early elections will have to be held by February.

Polls put the far-left Syriza party ahead of Samaras’ conservative New Democracy. The former wants to tear up Greece’s bailout agreements, stop budget consolidation and write off part of the country’s debt. It also opposes the liberal economic reforms Samaras has enacted under pressure from other European Union countries.