trial balloon
From Longman Dictionary of Contemporary Englishtrial balloonˈtrial balˌloon noun [countable] something that you do or say in order to see whether other people will accept something or not Senator Lott is floating trial balloons to test public opinion on the bill.Examples from the Corpustrial balloon• It was Mr Florio, elected in 1989, who floated himself as a trial balloon for Clintonomics.• A good cabinet officer will take a policy proposal, put a trial balloon out.