Speaking to journalists at the Seimas on Tuesday, Butkevičius said that the Social Democrats were open to all parties but refused to specify who could join the projected three-party coalition.
"We do not only cooperate with the Labour Party but also with the Order and Justice party; however, we might also invite other parties to the ruling majority," he said when asked about the decisions made by the party's board on Monday evening.
The Social Democratic leader said it was the party's initiative, which has not yet been discussed with potential coalition partners.
Butkevičius said doors to join the coalition were open to all political parties that won parliamentary mandates in the recent parliamentary elections.
"We haven't decided yet, I cannot make the decision unilaterally, without discussing it with my colleagues," Butkevičius said.