John McCainJohn Sidney McCainTrump's dangerous Guantánamo fixation will fuel fire for terrorists Tech beefs up lobbying amid Russia scrutiny Ad encourages GOP senator to vote 'no' on tax bill MORE's stance on climate change has proven to be controversial with at least one group of economic conservatives, as the Club for Growth today criticized the Arizona Republican's support for a cap-and-trade system.

The concept would set mandatory limits on greenhouse emissions, and allow companies that pollute less to sell their permits to those that pollute more.

"McCain