The party's executive committee is expected to formally initiate preparations for the EU elections on Friday and Vajgl is expected to be named the top candidate, Erjavec said on the margins of an informal EU ministerial.

Vajgl, 75, is a two-term MEP who has previously served as ambassador, foreign minister and member of the Slovenian National Assembly.

As MEP he is an individual member of the European Democratic Party (EDP) but Erjavec said DeSUS as a party would formally join EDP at a congress in Bilbao, Spain next week.

The EDP is one of the two parties which form the Alliance of Democrats and Liberals in Europe (ALDE), a grouping that all three DeSUS partners in the ruling coalitions are members of.

Despite the close alliance, Erjavec said there had been no motion to join forces with the other ALDE members, which are preparing a joint slate.

"We did not get an invitation, but this is no big deal," he said, noting that DeSUS was the only liberal party in Slovenia with an MEP anyway.