He held the post of praetor in 77 BCE and was elected consul in 74 BCE with
Lucius Licinius Lucullus. Though he was "a man altogether unwarlike," he received the new province of Bithynia as his proconsular command. He was given a fleet to protect his province (Appian, Civil Wars 71). When
Mithridates invaded Bithynia, he fled to Chalcedon. Because he was inexperienced in war affairs, he sent out his prefect, Nudus, to confront Mithridates. Nudus lost his position and was driven back to the gate with his men. With Nudus and Cotta holed up in the walls of Chalcedon, Mithridates made good advances.