According to Virant, the motion was backed by the MPs of the coalition Citizens' List (DL), People's Party (SLS), Pensioners' Party (DeSUS), the opposition Social Democrats (SD), both minority MPs, independent MP Ivan Vogrin and 20 of the 26 MPs of the ruling Democrats (SDS).

The reason why not all SDS MPs signed the proposal is of a rather technical nature, Virant said, explaining that not all of them had been present at the relevant session of the deputy group.

Virant said that the support to the constitutional changes was therefore close to the required 60 votes and that only NSi votes were missing.

In order for the NSi to back the proposal, conditions for calling a referendum will have to be made tougher. The party proposes that the number of voter signatures needed to initiate proceedings for a referendum be raised from 2,500 to 10,000, and that these signatures be verified at the respective administrative unit in a week.

The signatures would then be included in the final quota of 40,000 signatures needed to call a referendum.

This proposal will be discussed next Wednesday, said Virant, who is upbeat that a compromise solution will be found then.

No party opposes toughening the conditions for calling a referendum, only the exact number of signatures needed and the time frame in which they must be collected has to be agreed on, he explained.

Meanwhile, the opposition Positive Slovenia (PS) has distanced itself from the project, although some sources say the party might back the changes at the end of the day.

Virant said he had already called a session of the parliamentary Constitutional Commission for 3 October. He expects that the start of the procedure for the constitutional changes will be set then.

In that case, this decision could be put to a vote in parliament in October and the next session of the Constitutional Commission could be held in November. The National Assembly could then pass the motion in December at the latest, Virant said.

He believes that an agreement on the constitutional changes would show "that we are capable of reaching an agreement on something after all and overcome the coalition - opposition divide".

Moreover, the changes would for the most part prevent the use of a referendum as a tool for political games and undermining of reforms, the speaker added.