In Shakespeare's Coriolanus, what are the primary reasons for Coriolanus' failing to become consul?

There are many factors that play into Coriolanus losing the consulship. For one, he treats the commoners with disdain. When they complain about starvation, he greets them by asking, “What's the matter, you dissentious rogues, / That, rubbing the poor itch of your opinion, / Make yourselves scabs?” Coriolanus threatens to slaughter them for their rebellious proposals, mocking and insulting them for the audacity to be hungry. He believes they deserve to be hungry because...

There are many factors that play into Coriolanus losing the consulship. For one, he treats the commoners with disdain. When they complain about starvation, he greets them by asking, “What's the matter, you dissentious rogues, / That, rubbing the poor itch of your opinion, / Make yourselves scabs?” Coriolanus threatens to slaughter them for their rebellious proposals, mocking and insulting them for the audacity to be hungry. He believes they deserve to be hungry because they are so cowardly and useless.

Coriolanus is reluctant to follow the tradition of asking for the people’s voices. He does not think they are important enough to have this right, and he appears to be bashful about showing them his scars (a part of the ritual). Whatever the case, he responds to them with sarcasm and scorn. Coriolanus says to himself, “Most sweet voices! / Better it is to die, better to starve, / Than crave the hire which first we do deserve.” While he finds the experience to be debasing, and he refuses to reveal his wounds, Coriolanus continues to ask for their votes.

Because of his attitude towards the plebeians, the sneaky senators Brutus and Sicinius easily convince the crowds to rescind their endorsement. Brutus and Sicinius worry about Coriolanus’s cruel attitude, but, more importantly, they are concerned about keeping their power. They remind the commoners that Coriolanus might be a hero, but he also despises them. They even instruct the crowd how to act when they confront Coriolanus, directing them to rail against Coriolanus and to paint the two of them in a positive light.

As you can see, Coriolanus loses the position of consul because of his proud personality and attitude, but he is also a victim of the swayable mob and the calculating senators.