The Bulgarian Socialist Party (BSP) has handed back the mandate to form a new government and lead the country out of the current Parliamentary crisis.
"I will not use the opportunity [to form a cabinet," Ninova has said before handing out a statement to Plevneliev to confirm the decision.
Ninova is accompanied by two core BSP members, Angel Naydenov and Zhelyo Boychev.
Bulgaria's Parliament Chair Tsetska Tsacheva and a delegation of MPs will pay an official visit to Romania on June 8-9, 2015.
On June 8 Tsacheva will meet with Valeriu Zgonea, Speaker of the Chamber of Deputies of the Romanian Parliament, according to the press office of Bulgaria's government.
The meeting will also be attended by Romania's Prime Minister Victor Ponta.
The Bulgarian Parliament decided on Wednesday to continue the construction of the fence at the border with Turkey without launching a public procurement procedure.
The members of parliament approved the amendments to the Public Procurement Act at first and second reading without discussions, the news website Dnevnik reports.
Cabinet members arrived at the Council of Ministers for what is expected to be their last session before Prime Minister Plamen Oresharski steps down.
Earlier this month Oresharski picked July 23 as the most suitable date for the government to submit its resignation.
However, ministers have repeatedly sent mixed signals as to whether this could happen on Wednesday.
Macedonian Defense Minister Zoran Jolevski is to arrive on an official visit to Bulgaria.
After the official welcoming ceremony in front of Monument to the Unknown Soldier in Sofia, Jolevski will have a meeting with his Bulgarian counterpart Angel Naydenov, according to reports of the Bulgarian National Television.