Sen. John McCainJohn McCainGOP senators split over Cruz's aid on campaign trail Why a power grid attack is a nightmare scenario Senate fight brews over Afghan visas MORE (R-Ariz.) said Wednesday that immigrants living in the United States illegally are not going home, and that the U.S. has no practical way of forcing them to leave.
"They're not going home. And so why don't we give them a path to citizenship," McCain asked at Harvard University’s John F. Kennedy Jr. forum.
"There are not enough buses to deport them," he added. "It's de facto amnesty."
Kennedy and McCain had worked on a comprehensive bill in 2005 that eventually made it into a 2007 measure that failed to make it to a Senate vote.
McCain was a member of the "Gang of Eight," a group of senators that helped push an immigration reform bill through the Senate last year. House GOP leaders have refused to take up that version.
The senator emphasized the bill does not provide automatic amnesty.
"It's really tough," he said, adding it would take years for people's status to change. "If you keep these people in the shadows, it is a stain on America’s honor."
McCain also repeated his previous prediction that "the Republican Party will never win another nationwide election unless we enact comprehensive immigration reform."