What was the most powerful governing body in the Roman Republic?

The people that have that kind of power was the senate which at the time had basic control over everything since they did all the voting. except when ceasr was in power he gave himself absolute power over everyone and did everything that he wanted. But when he had been killed his adopted son went into to the leadership roll who was Augustus but he didn't want to make the same mistake his father made so he did what the senate wanted him to do which made them give him complete power but he did not ask for this he just waited for them to give it to him. So yes the senate has all of the power in Rome if you go by this.