“I think the tide has kind of turned in some ways against defense thanks to the tea party. They’re so much against any kind of spending that they don’t exclude defense from that,” Isaacs said.

“To cement his legacy, he needs another nuclear reductions agreement,” said John Isaacs, executive director of the Council for a Livable World, a nonprofit advocacy group that seeks to eliminate nuclear weapons. “But if there’s no missile defense agreement, he can’t get one. It’s become the key to further progress.”

“One senator can make a difference in this system and when that senator dies, retires, or is defeated, that could have a big impact. Such will be the case with Jon Kyl,” said John Isaacs, executive director of the Council for a Livable World (CLW), which advocates on issues related to nuclear proliferation.