Omerzel is alleged to have breached the act on integrity and prevention of corruption by failing to submit data on a company he owns, which would have immediately put the firm on the list of companies that have restricted access to state-funded projects.

The opposition say he also mislead the public about the dealings of his company with the state-owned motorway company DARS, and picked a contractor for licence plates whose offer was twice as expensive as the competition.

Omerzel's conduct is a huge problem in a country that has unfavourable corruption ratings, SDS deputy Andrej Vizjak said. "He is either naive or he has lost the sense of responsibility and justice," added New Slovenia (NSi) president Ljudmila Novak.

While interpellations are typically little but an opportunity for the opposition to vent their grievances during the day-long televised debate in parliament, Omerzel's case could be different.

The Pensioners' Party (DeSUS) indicated today it would not back Omerzel, though it did not clarify whether the deputies would abstain or actually vote in favour of the ouster motion. Yes-votes by DeSUS would bring the minister down.

Omerzel lost support in the coalition after it was revealed that his firm Lastinski was planning to extend its contract with the state-owned motorway company DARS despite Omerzel's claims it would terminate cooperation.

He was making his case for staying on to coalition deputy groups today, but the DeSUS deputy group leader Franc Jurša said the party would "not take responsibility. The prime minister should resolve the matter."