Sen. John McCainJohn Sidney McCainRubio asks Army to kick out West Point grad with pro-communist posts The VA's woes cannot be pinned on any singular administration Overnight Defense: Mattis offers support for Iran deal | McCain blocks nominees over Afghanistan strategy | Trump, Tillerson spilt raises new questions about N. Korea policy MORE (R-Ariz.) released a new radio ad Wednesday to air in New Hampshire highlighting his long-held stance that global warming is a problem government should deal with.

McCain, who has led congressional efforts to fight global warming in the past, says he has listened to New Hampshire voters on the issue.

"Not everyone heard you, but I did," McCain says in the ad. McCain emphasizes global warming as a national security issue as well as an environmental one in the 60-second radio spot.

In January McCain reintroduced climate legislation with Sen. Joe Lieberman (I-Conn.), with Democratic presidential hopeful Sen. Barack Obama (Ill.) as an initial cosponsor.