Yes,FDR did trick the US into supporting WWII.Europe was heavily engaged in the war and needed support from the US plus FDR knew it would be good for the economy and help finally lift the economy out of the depression because workers would be needed for war production and other activities.
Support by United States citizens for entering World War II did not really happen until something really shook everyone up--the bombing of Pearl Harbor. When this happened, Americans suddenly realized that they could not stay out of the war. An unwarranted attack on American soil made them immediately realize they could not just stay passive. That being said, FDR definitely helped keep morale up for staying in the war, by doing things such as his fireside chats.