Greek Prime Minister Alexis Tsipras faces a mounting backlash at home ahead of the referendum he called on Sunday.

Criticism of his choices grew Thursday, as lawmakers of the coalition government parties and cabinet ministers openly distanced themselves or implied that they would resign over diverging views on the planned steps ahead.

The Leftist leader appeared defiant on Wednesday in a televised message to the nation that the referendum would go ahead and that Greece's position in the euro zone was not at stake if Greeks voted "No" as he urged.

Tsipras argued that the referendum was a vehicle to pressure lenders for a better deal for the Greek people.

However, pressure is mounting on the Greek leader with the country in arrears to the International Monetary Fund since Tuesday midnight, emergency liquidity aid to crumbling Greek banks frozen since the weekend, capital controls and reports of the elderly fainting in long queues as they wait to get a small portion of their pensions.

After Wednesday's Eurogroup teleconference, European Union officials said negotiations would resume after Sunday's referendum.

On Thursday, at least four legislators of the junior Greek coalition partner Independent Greeks (ANEL) party publicly said they would vote Yes on Sunday.

Vassilis Kokkalis said he kept silent initially because he had been assured by the government there would be no turbulence in the banking system.

Costas Damavolitis, Dimitris Kammenos and Nikos Mavraganis joined in calling on Greek President Prokopis Pavlopoulos to call a council meeting of political leaders and cancel the referendum.

"We are at war. Whoever cannot take it should leave," ANEL party leader and current Defense Minister Panos Kammenos said.

Shortly afterwards a party statement was issued announcing that Damavolitis was the first member of parliament to be expelled from ANEL's parliamentary group. The party asked the deputy to quit the parliament and return his seat. In case Damavoliotis refused, the two-party coalition would remain with 161 seats in the 300-member strong assembly.

"We need to respect democratic procedures... we will be all united in efforts to overcome the debt crisis," Tsipras commented after his visit to the Defense Ministry.

Tsipras will also address a rally in favor of a No vote Friday evening in front of the parliament.

His visit to the Defense Ministry was made amid media reports that Kammenos had threatened to resign this week if Tsipras accepted cutbacks in defense expenditure as creditors requested. On Thursday, the Premier said the Greek government would decide where and how any cuts would be made.

Meanwhile, Health Minister Panagiotis Kouroumblis, a member of Tsipras' radical Left SYRIZA party, implied during a press briefing that he would step down if the government accepted cutbacks in the health sector.

Finance Minister Yanis Varoufakis said in statements to media Thursday that he would resign if Greeks voted Yes on Sunday.

"If Yes prevails, I will not be finance minister on Monday evening. I'd rather cut my arm off than sign a new deal that does not restructure public debt," he stated.

Deputy Parliament Speaker Alexis Mitropoulos said Thursday that Tsipras should remain in his position even if people vote Yes because "it would be inconceivable for him to desert the Greek people in their toughest decision."

Government spokesman Gavriil Sakellaridis, State Minister Nikos Pappas and other cabinet ministers backed this line assuring that after the referendum regardless of the outcome a good agreement would be clinched, banks would reopen and depositors would not face the threat of a haircut on their savings.

Five former prime ministers, who governed Greece in the past 25 years, issued statements in the past few hours urging Greeks to vote Yes to a debt deal. Konstantinos Mitsotakis (1990-1993), Costas Simitis (1996-2004), Costas Karamanlis (2004-2009), George Papandreou (2009-2010) and Panagiotis Pikrammenos (2011) made pleas for national unity in such critical times. Some openly suggested the formation of a national unity government to take over.

"The referendum has meaning when it does not divide," President Prokopis Pavlopoulos commented Thursday, stressing that Greece's membership in the European common currency zone was the only option to ensure financial stability and return to growth and prosperity.