The maiden congress of the Alliance of Alenka Bratušek will elect party leadership, adopt a statute and lay out platform guidelines.

Bratušek is forming a party after she was defeated as leader of the Positive Slovenia (PS) by party founder, Ljubljana Mayor Zoran Janković in late April.

The outcome of the vote at the PS congress prompted Bratušek to stand down as PM and split the largest parliamentary party into two groups that are now heading to the polls as rivals.

The rift further increased the fragmentation left of centre, which was one of the reasons for the poor showing of the left-leaning bloc in Sunday's elections to the European Parliament.

Bratušek vowed to make her best effort to bring together akin parties so they could stand jointly in the general election. A recent poll suggested her party could win close to 5% of the vote.

After Bratušek had already met some of the potential allies in the run-up to the congress, talks are expected to be stepped up in the coming days, as the snap vote is expected to be held as early as July.

Bratušek's party would build on a social and liberal platform. "The Alliance of Alenka Bratušek will unite everyone who believes Slovenia can be a successful economy as well as a welfare state," she has said.

One of the guests expected at the congress is Angelika Mlinar, an ethic Slovenian from Austria who has been elected Austria's MEP on the ticket of the liberal party NEOS after being elected MP last year.