Hours before the nomination was made public, Maliki delivered a late night televised address in which he threatened Massoum with legal action for not choosing him as a nominee and mentioned the army as protector of the constitution.
While he delivered his speech, Iraqi forces and tanks increased their presence in Baghdad's Green Zone, prompting the question of whether a coup was imminent.
Gen. Halgurd Hikmet, a spokesman for the Kurdish Peshmerga forces, admitted, "We're all worried about a coup d'état," while adding that the Kurdish division of the Iraqi Army is also providing security in Baghdad. "Maliki has to know that we have two major units of our troops guarding the Parliament and the Defense Ministry."
There were no further signs by Monday afternoon of Maliki attempting to use the military to remain in office.
According to Iraq's constitution, the newly-appointed Prime Minister Abadi has 30 days to form a unity government.
Maliki will, in the meantime, serve as caretaker leader and commander-in-chief of the Iraqi security forces.
U.S. Secretary of State John Kerry expressed support for the Iraqi president on Monday, noting "it's up the Iraqi people to decide who their prime minister is going to be ... And at this moment, Iraq has clearly made a statement that they're looking for change."
Kerry cautioned Maliki against a coup, warning, "There should be no use of force, no introduction of troops or militias into this moment of democracy for Iraq. Iraq needs to finish its government formation process and the United States will do everything possible in order to support and uphold the constitution that the new president is, in fact, following appropriately."