In the letter circulated by the weekly Reporter on its web site on Sunday, Šušteršič argued that the party should not form a government with the PS but remain in the opposition. He suggested the attempts by the PS to call referenda on the bad bank and sovereign holding laws meant that parties did not share compatible platforms.

Šušteršič reportedly sent the letter to his party colleagues on Wednesday, in which he added that the PS continued to have doubts about the bad bank and could attempt to halt the project.

"Given that the government has already adopted the acts of incorporation of the Bank Assets Management Company and appointed the non-executive directors and is preparing the implementation regulations, such thinking means that Slovenia would take several steps back and lose precious time in dealing with the credit crunch," Šušteršič said.

Moreover, he said that the demand by the PS to request a delay in the passage of the asset management strategy for the new Slovenia Sovereign Holding could lead to a "delay in privatisation" and hurt Slovenia's credibility among international investors.

Šušteršič also claimed in the letter that the fact that the current government of Janez Janša adopted the strategy was cited by Bratušek as the only reason for the PS's demand.

Moreover, he argued in the letter that the difference in platforms between the DL and the centre-left parties was too wide to enter a centre-left government, highlighting that the DL did not leave the Janša government over content but over findings of the anti-graft watchdog against Janša.

The DL cannot adopt an about turn overnight and act as if Janša is the biggest danger to Slovenia and that his removal from politics is the main goal, added Šušteršič.

The DL decided to endorse Bratušek for PM at Thursday's session of its council under the condition that suspended PS leader Zoran Jankovič, who was also singled out in the graft report, resigns for good.

Responding to Šušteršič's letter on Thursday, DL leader Gregort Virant said that pressing ahead with the Janša government is "something so unacceptable that it must be resolved, even at the price of negotiating on a centre-left government (of course, after the resignation of Zoran Jankovič as PS leader)."

Virant said that he agreed with Šušteršič that early elections would be the best option, but added that conditions for that were not fulfilled.

While the DL has decided to back Bratušek, it has not yet confirmed it would join her government, saying that a decision on this would depend on the programme of the new government.