Italy’s prime minister, Mario Draghi, is expected to confirm his resignation after three key parties in his broad coalition did not participate in a confidence vote on the conditions he set for his government continuing.

The former European Central Bank chief told the senate earlier on Wednesday that the survival of his unity administration hinged on “rebuilding the pact of trust” and spirit of cooperation of its early months, and asked for a vote on this basis.

Draghi offered his resignation last week after the Five Star Movement (M5S), a key component of his broad coalition, snubbed a vote on a €26bn cost of living package.

His resignation was rejected by the president, Sergio Mattarella, who asked him to address parliament in an attempt to avert what would be the collapse of Italy’s third government in three years.

The move instead widened the rifts between the squabbling parties, with Matteo Salvini’s far-right League and Silvio Berlusconi’s Forza Italia demanding a new Draghi government without M5S.

Draghi has said several times that he would not lead a government without M5S, but would also not accept ultimatums.

As tensions mounted throughout the day, the League and Forza Italia said they were “surprised” when Draghi announced his government’s fate would be determined with a confidence vote on a resolution requested by centrist senator, Pier Ferdinando Casini, that called for the approval of Draghi’s conditions.

Both parties said they would not be present for the vote. M5S then followed suit. “Over the past 18 months all of our measures have been dismantled,” M5S senator Mariolina Castellone said. “Let’s remove the inconvenience.”

The vote passed in the senate on Wednesday evening but even though Draghi still has a majority, he will likely confirm his resignation.

“I think it’s over,” said Wolfango Piccoli, co-president of the London-based research company, Teneo. Draghi will address the lower house of parliament on Thursday morning, where he is expected to announce his resignation as an act of respect towards parliament, before going to Mattarella. Piccoli said: “Barring a miracle, that’s the outcome.”

He added: “It’s not a question of a majority at this point because he always had the majority – the question here is about the politics, meaning there was no movement from the political parties to meet his conditions to create a new sense of trust, so what we’ve seen is three parties turning their backs on him.

“All the speeches by the League, M5S and Forza Italia today were pre-election speeches.”

Draghi’s potential resignation would come despite a groundswell of public support for him to remain in the post. There have been declarations from more than 1,500 mayors from across the political spectrum and various labour unions, a signal of public support Draghi said was “unprecedented and impossible to ignore”.

He had also urged unity so that the government could face key challenges, such as the war in Ukraine, the energy crisis, social inequality and the enactment of reforms needed to obtain the next tranche of the €200bn Italy is due to receive from the EU’s post-pandemic recovery fund. He also rebuked his coalition partners for infighting and point-scoring over recent months.

If Draghi confirms his resignation then Mattarella could ask him to stay on as interim prime minister. However, analysts say that Mattarella would most probably dissolve parliament and call elections for as early as the end of September.

A report this week on recent surveys said that in the event of early elections, a coalition led by the far-right Brothers of Italy and including the League and Forza Italia could easily secure a majority.