During a televised weekly speech on Wednesday, Maliki called President Fouad Massoum's nomination of Haider al-Abadi as the next prime minister "a constitutional violation" and a "conspiracy."
Maliki insists it is his "ethical and patriotic duty" to remain in office until a federal court can rule on the legality of Abadi's nomination.
According to the Iraqi constitution, Abadi has 30 days from his appointment to form a unity government.
Maliki, in the meantime, will serve as caretaker leader and commander-in-chief of the Iraqi security forces. The outgoing prime minister has displayed his power by deploying security forces throughout Baghdad, raising questions of how far he will go to hold onto his office.
The West has responded to the political turmoil and ongoing terrorist threat posed by the Islamic State by urging Abadi to move swiftly in forming an inclusive government representative of all Iraqis.
On Tuesday, NATO Secretary-General Anders Fogh Rasmussen echoed a message conveyed by the U.S., that "inclusive government is essential in defeating the Islamic State in Iraq and the Lebant, which represents a threat to the security and stability of the region as a whole."