The leaders, Zoran Milanovic of the Social Democrats (SDP), Radimir Cacic of the People's Party (HNS), Ivan Jakovcic of the Istrian Democratic Party (IDS) and Silvano Hrelja of the Pensioners' Party (HSU), said at a news conference after their meeting that this coalition offered a clear alternative and strategy for Croatia's development.
They also expressed conviction at their victory at the next parliamentary elections.
We are ready for elections whenever they will be held, although we think that "the situation has ripened for new elections", Milanovic said adding that as long as the ruling coalition has the majority, the Opposition is willing to have talks and cooperation,
Milanovic described the Opposition coalition which the HSU joined today as "different, more determined and prepared for changes for the sake of Croatia's well-being".
The SDP chief said that it would be important to initiate the economic development and encourage investment funds in these times.
He said that today's talks had also revolved around the decentralisation of the state.
In response to reporters' questions whether they had today considered developments following yesterday's decision of the Croatian Social Liberal Party (HSLS) to leave the ruling coalition led by the Croatian Democratic Union (HDZ), Milanovic said that there had been no mention of the HSLS today.
Radimir Cacic of the HNS joined in the calls for stimulating the economic revival and he also called for working on "a new wave of optimism".
The HNS leader said nothing had been done to reduce the public spending, and he warned that the situation was not good when in Croatia, working-age population accounted for 57 percent of the total population, whereas in Germany this figure was 75 percent.
IDS chief Jakovcic expressed satisfaction with this coalition's vision for the "certain winners at the parliamentary elections".
HSU leader Hrelja said he liked the approach this coalition had in treating problems of Croatian citizens.