Argument is arguably the weakest of the three levers because many audiences cannot be persuaded unless they trust the speaker and feel a compelling emotion, but they don't need detailed reasoning about evidence. Instead, they will trust the speaker to have done that.
However, it is a very important lever if the speaker actually wants to make good decisions.
Reasoning, logic, and evidence are the tools we use to build an accurate model of the world.
A speaker can definitely persuade an audience without ever using sound reasoning, but doing so increases the odds that what they want the audience to do is bad.
Ideally, a speaker has an argument to justify their position even if they choose not to use it as part of their persuasive approach.