Pivniceru resigned on Wednesday to take on a position of judge at the Constitutional Court.
Ponta may serve as interim minister for 45 days and must nominate a new justice minister.
Ponta said Wednesday that, in his capacity as interim justice minister, he plans to nominate a new prosecutor general and anticorruption chief prosecutor after talks with the head of state and the High Council of Magistrates. The previous nominations, submitted by Pivniceru, have been rejected both by the head of state and the High Council of Magistrates.