Which of these had the power of veto in the Roman Republic?

A veto (Latin for "I forbid") is the power (used by an officer of the state, for example) to unilaterally stop an official action, especially the enactment of legislation.

The institution of the veto, known to the Romans as the intercessio, was adopted by the Roman Republic in the 6th century BC to enable the tribunes to protect the mandamus interests of the plebeians (common citizenry) from the encroachments of the patricians, who dominated the Senate. A tribune's veto did not prevent the senate from passing a bill but meant that it was denied the force of law. The tribunes could also use the veto to prevent a bill from being brought before the plebeian assembly. The consuls also had the power of veto, as decision-making generally required the assent of both consuls. If one disagreed, either could invoke the intercessio to block the action of the other. The veto was an essential component of the Roman conception of power being wielded not only to manage state affairs but to moderate and restrict the power of the state's high officials and institutions.