In a letter addressed to SMC leader Zdravko Počivalšek and distributed to media outlets, Klampfer says her decision to quit is due to her disapproving of how the party is being run, in particular after Prime Minister Marjan Šarec's resignation two weeks ago.

Listing her achievements as minister of labour, the family, social affairs and equal opportunities, Klampfer says that her discussion with Počivalšek the morning before Šarec's resignation showed that "work is not appreciated, that more than work it is populism that counts".

"Under your leadership, the party is increasingly moving course away from the views of people who brought the party the nobleness of socio-liberal values (...) My belief is being confirmed with daily calls by party colleagues who are getting ready to quit the SMC," she writes.

Noting that back in 2017 as the head of the Maribor administrative unit she banned a concert by Croatian ultra-nationalist singer Thompson, Klampfer says that she has never since received any support for her efforts from the party leadership, not even as she encountered problems as minister.

"As vice-president you have never engaged me in the party's work and this makes all the accusations and insults related to that all the more unacceptable. I have somehow reconciled myself to that, but what is happening today I cannot accept.

"We are negotiating on joining a right-wing government, with a completely different ideology. With a party that openly supports Thompson's ultra-nationalism and the far-right Hungarian Prime Minister Orban, who is being followed with concerns by whole Europe."

Adding that the SDS also denies climate change and has a different view of the Second World War, Klampfer says that she believes a person and politician needs to stay true to themselves and their values.

Arguing that despite the storms it has gone through, the party still has a lot of good and capable members who believe in solidarity and dialogue, and who are strangers to rightist ideology, Klampfer appeals to Počivalšek to reconsider where he is taking the party, and to listen to people.

Počivalšek responded with a written statement regretting the decision and expressing surprise. "Slamming the door may be momentarily likeable, but it is also politically immature," he said.

"True, the political circumstances have changed substantially in recent weeks, but this should not absolve the party's leadership of its responsibility to voters and deter it from looking for solutions for the benefit of the party."

He thinks the fact that Klampfer notified him of her decision at almost the same time as she informed the media sheds light on the true background of her decision - "yielding under the weight of public pressure on the SMC to subjugate its future political decisions to the interest of other parties."

Klampfer resigned after the party, set up shortly before the 2014 general election by Miro Cerar, a later prime minister who has served as foreign minister in the outgoing government, entered talks with the SDS in a bid to form a government coalition to replace the Šarec government.

As leader of the party until September 2019, Cerar had been ruling out a coalition with SDS leader Janez Janša. According to the right-leaning magazine Reporter, Cerar has written a letter to Počivalšek too, reiterating his opposition to a Janša-led government.

"Since entering politics I have always advocated the same principles and opposed the politics personified by Janez Janša," Cerar says in the letter.

"I obviously support the efforts by the SMC leader to lead dialogue with all parties but with the goal of forming a coalition to be led by a person who implements democratic values in practice and higher political culture. In case a government is formed under Janša's leadership I cannot take part in it."

Cerar also expressed regret that Šarec failed to justify their trust, arguing that he had not run the government in a unifying enough way, and failed to provide the conditions to smoothly continue the planned work and reforms.

Počivalšek said the SMC had always been liberal and tolerant to other opinions, which was why he saw Cerar's letter as "an expression of his own will and opinion, to which everyone in the SMC is entitled."

Before resuming talks with the SDS on Tuesday, the SMC met the LMŠ today to discuss the possibility for the two parties to run on a joint slate in a potential snap election. The details of the talks have not been disclosed yet.