Speaking at the party congress in Ljubljana, Janković said he was still to decide whether he would run for party president again.

He also hopes the there will be enough time for him to disprove allegations of the Corruption Prevention Commission, which has accused him and Prime Minister Janez Janša of systematic breaches of Slovenia's anti-corruption legislation.

Janković announced he will not be taking part in talks on a new coalition or negotiations on a technical government. This is an opportunity for everybody, both in the coalition and the opposition, to think about a new coalition or a technocrat government, he said.

But he stressed this did not mean he was bidding farewell to politics. He said he was neither withdrawing from politics nor from his party. He is also planning to stay on as the mayor of Ljubljana, an office he has held since 2006.

He said he had received many letters over the last couple of days urging him to resign in the name of "high moral standards". But he rejected them as he believes that resigning would give the impression he is admitting corruption. "I am not corrupt and not a crook," he said.

Speaking to the press after the congress, PS deputy group leader Jani Möderndorfer explained that the party rules do not include the instrument of "suspension", meaning that Janković actually "forfeited his leadership of the party, which means we must now call the election and choose a new president".

In the mean time, the party must choose a replacement for Janković from the ranks of the three vice-presidents - MPs Maša Kociper and Melita Župevc and Robert Golob, who is the CEO of electricity distributor GEN-I.

None of the three had so far indicated willingness to take the helm of the party. Möderndorfer said the decision would be made by the party council within a week.

Today's congress was dedicated to the party's manifesto, entitled the "Founding Charter of Positive Slovenia - Slovenia 2020". Janković labelled the document a plan that would "guide Slovenia out of apathy, fear, pessimism and onto the path of success and place it among the leading European countries".

As he explained, the document is an upgrade of the programme with which PS won the election in 2011. Among other things, the document calls for a fairer distribution of wealth, creation of added value, solidarity, more popular involvement in decision-making and a green development policy.

Jankovič also pointed to a new provision which envisages a formation of cooperatives in Slovenian ownership, which is designed to prevent governments from selling state assets.

Janković said the provision was necessary because the current government sees a clearance sale of state assets as the solution. This would make Slovenians servants in their country, Janković stressed.

He also thanked party deputies for the work they were doing in parliament. "If it wasn't for them in parliament, this country would have been much worse off than it is now."

Taking stock of 2012, he said the results were "very mixed". He said the pension reform was necessary and was the only positive achievement of the current government.

The 60-year-old Janković entered politics after being fired from retailer Mercator in 2005. Ljubljana's long-time mayor had first shunned national politics, but in October 2011, just months before the early parliamentary elections, he created his own party (PS), which emerged the surprise winner with 28.5% of the vote.

He however failed to put together a ruling coalition and returned to the City Hall in March 2012 while still remaining at the helm of Positive Slovenia and an informal leader of the parliamentary opposition.