The ZL filed into procedure on Monday a motion for a parliamentary investigation of the most expensive energy project in the country, which is already the subject of several criminal investigations.
The motion secured cross-partisan support, with MPs of the coalition Party of Miro Cerar (SMC), Pensioners' Party (DeSUS) and Social Democrats (SD) as well as the opposition New Slovenia (NSi) and Alliance of Alenka Bratušek (ZaAB) contributing signatures.
A total of 67 MPs signed it, seven more than the required two-thirds majority of 60.
"It is high time we conducted a thorough analysis of what has happened," said ZL deputy Matjaž Hanžek, who said the inquiry must come up with tangible conclusions.
Hanžek said that the inquiry had no intention of replacing the ongoing police investigations into the project and would seek political culpability and the reasons for the massive cost overruns.
Fellow opposition New Slovenia (NSi) announced the party was on board the inquiry into what MP Jernej Vrtovec described as "a monument to Slovenian corruption". The fallout of the TEŠ6 project was being felt by the energy industry as a whole in Slovenia, he said.
The building of the new generator at the Termoelektrarna Šoštanj (TEŠ) coal-fired power station is blamed for severely draining the finances of the state-owned HSE energy holding due to mounting costs.
The generator, which was recently connected to the grid, also faces uncertainty about its long-term feasibility related to the economics of producing and burning coal from the nearby Velenje coal mine.
Hanžek said the goal of the inquiry was "to establish patterns of behaviour and the link between private interests and 'state capture'" in the project.
SMC deputy Bojan Dobovšek said that the biggest deputy group decided to endorse the motion because of its commitment to fighting white collar crime. In addition to the criminal investigations, it is only right that political culpability is investigated, said Dobovšek.
This was echoed by Primož Hainz of DeSUS, who said that the inquiry would seek to uncover what went on in the background of the mega energy project.
ZaAB said it wanted to get to the bottom of actions of MPs in the previous term when they approved a EUR 440m state guarantee for the project.
Prime Minister Miro Cerar also responded to the motion by saying that his government supported a parliamentary probe of the TEŠ6 project. Cerar made the announcement on the margins of a meeting dedicated to the fallout of the liquidation of TET, a smaller coal-fired power plant in Trbovlje (central).
Hanžek said the opposition Democrats (SDS) and the two minority representatives did not contribute their signatures. The ZL has been in talks with the SDS, but the two parties could not find common ground, he said.
SDS vice president Zvonko Černač said that the party was in favour of all efforts to publicly disclose the causes of the cost overruns, but feared that the parliamentary probe would not focus on the key issues but would instead serve as a means of promoting the ZL platform.
The parliamentary inquiry commission will formally be set up when the National Assembly gets acquainted with the motion at its next sitting.