Sens. Edward Kennedy of Massachusetts, left, and John McCain of Arizona, talking during a news conference on their effort at a comprehensive immigration overhaul in 2006. Both men have since died of an aggressive form of brain cancer.

Sens. Edward Kennedy of Massachusetts, left, and John McCain of Arizona, talking during a news conference on their effort at a comprehensive immigration overhaul in 2006. Both men have since died of an aggressive form of brain cancer.