Sen. John McCainJohn McCainSchwarzenegger tweets to McCain: 'You'll be back' Trump called McCain to wish him well after cancer diagnosis Rand Paul opens door to backing healthcare bill on key hurdle 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.