Every Republican candidate is either a dangerous extremist or a completely unintelligent .

So much for reasoned debate! The Heartland Institute, a controversial group known for trying to discredit climate science, has unveiled billboards that compare people concerned about global warming to mass murderers such as Osama Bin Laden.The Chicago-based group said its first billboards featuring Ted Kaczynski-- whose mail bombing campaign spanned nearly 20 years and killed three people and injured 23 others-- began appearing Thursday along the the inbound Eisenhower Expressway in Maywood, Ill.FOLLOW: Green House on Twitter"The most prominent advocates of global warming aren't scientists," Heartland's president, Joseph Bast, said in a news release. "They are Charles Manson, a mass murderer; Fidel Castro, a tyrant; and Ted Kaczynski, the Unabomber." The group said other "global warming alarmists" who may appear on future billboards include Osama bin Laden and James J. Lee, who took hostages inside the headquarters of the Discovery Channel in 2010.In a statement, the group says it chose these "madmen" because what they've said "differs very little from what spokespersons for the United Nations, journalists for the "mainstream" media, and liberal politicians say about global warming." It added: