The most powerful way to get someone to agree with your idea is to ask them the leading question, and have them tell you.
Ronald Regan used this technique a lot. He did not tell the American people “your economic situation has deteriorated over the last 48 months”, instead he asked the famous question during his election campaign: “Are you better off now than you were 4 years ago?”. The answer was a resounding “NO” and he was elected.
Asking the right question can prompt a favourable, almost pre-deternmined response, but the formulation of the words to convey that response provokes a deeper, more intensive processing of the question. This leaves less room for ambiguity and uncertainty in the way the receiver responds to the question, and considerable committment to the answer.
I have also found it a great way to generate engagement at the opening of a presentation.