In this campaign video, Sen. John McCainJohn Sidney McCainTrump's plan to claw back spending hits wall in Congress Defense bill moves forward with lawmakers thinking about McCain How House Republicans scrambled the Russia probe MORE (R-Ariz.) said he'd be a leader in global warming reform if he's elected president.

"Americans, I don't think, appreciate the fergility of our environment nor do they understand completely how vulnerable we are in our dependency of foreign oil," McCain said.