"I don't want to just wonder about the nation's future, but want to co-shape it as the president of all Slovenians," Pahor said.

"From the moment I entered politics I knew this will happen one day. Ever since then I had the funny feeling it's my destiny. And it obviously is. Today the time is ripe," Pahor said to the applause from the delegates.

Yet contrary to expectations, Pahor did not give up on his bid for a fifth term at the helm of the party, arguing that the two posts were not incompatible.

He believes that his decision is at the moment the best solution for the party. "It's now one of those periods when the party cannot get limited by apparent, exiting political possibilities, but needs to change that framework."

Pahor is challenged by three other candidates for the top party job at today's congress, which has heard calls for a change of leadership and a clearer positioning of the party on the left.

The other main contestants are Patrick Vlačič and Igor Lukšič, who both served as ministers in Pahor's 2008-2011 government, while Zlatko Jenko is not seen as a strong candidate.

Lukšič said that he was there "to win", while Vlačič said this was "an important day for Slovenia" and Pahor said he was "bidding farewell to this term with a satisfaction," regardless of the outcome.

Some of the 350 delegates gathered in Kočevje highlighted Pahor's achievements, but even more voiced criticism of the party's work and especially of the current leadership, calling for change and a shift away from Pahor's centrist and pro-liberal reform policies.

Pahor is estimated to enjoy the support of a half of the delegates, while the youth wing, representing around 10% of the delegates, backed Vlačič, the transport minister in the 2008-2011 government.

Yet most of the delegates will not make the decision until after the presentations of bids. The vote is expected to be tight, and will likely require a second run.

Aside from Pahor, bids for the autumn presidential election have been announced by incumbent President Danilo Türk and Milan Zver, an MEP for the senior coalition Democrats (SDS).

Two other hopefuls are Zmago Jelinčič, leader of the non-parliamentary National Party (SNS), and Marko Kožar, an independent with a string of unsuccessful presidential bids.

Pahor had already mulled standing in the 2007 presidential election, but then decided to take his party to the 2008 general election, which he won.