Putting such a motion on the parliament's agenda requires signatures of one fifth of MPs (or of some 30 deputies), The proposal substantiated by 58 signatures was thus automatically added to the agenda.
The government is expected to give its position on this proposal within eight days, and the parliament is to vote on it within 30 days.
Although it was earlier speculated that the SDP would seek a no-cofidence vote on the entire government, the motion is only about the no-confidence vote in PM Kosor whom the Opposition holds responsible for a deteriorating economic situations, a stalemate in reforms and loss of confidence among citizens caused by scandals and in-fighting in the ruling Croatian Democratic Union (HDZ).
The signatures were collected among parliamentarians of the Croatian People's Party (HNS), the Istrian Democratic Party (IDS), the Croatian Pensioners' Party (HSU), the Croatian Party of Rights (HSP) and the Croatian Labour Party, apart from SDP representatives.
In response to reporters' questions what the motion is aimed at achieving when it is not likely that the enough votes will be mustered to topple the premier, SDP leader Zoran Milanovic said today that this would be still discussed.
"Our job is that in the parliament we discuss it," he said.
The HDZ parliamentary caucus later in the day described the motion as harmful for Croatia's interests.
It also dismissed as a lie the SDP claims that Kosor talked with her Hungarian counterpart Viktor Orban on the phone about possibilities for modifying the shareholders' agreement between Croatia's INA and Hungary's MOL.
The caucus's head, Andrija Hebrang, said that the request for the government's ouster might affect Croatia's accession negotiations with the European Union.