In any democratic country, I guess, sometimes politicians want to see whether an idea is acceptable in the prevailing public opinion, but at the same time they don't want to reveal their position on an issue until they are sure of the outcome.
Something like this happens in case of controversial issues where politicians want their action placed in a positive perspective and where to express an unpopular idea may be problematic.
So, my question is, is there a term for when a politician sends an anonymous idea to see whether the public is receptive?