President-elect Donald Trump's hard-line immigration stance was a central part of his campaign message in 2016 -- and he said in an interview airing Sunday that he plans to immediately deport approximately two to three million undocumented immigrants. Asked whether he really plans to build a wall along the U.S.-Mexico border -- a proposal that served as a centerpiece of his campaign message -- Trump replied, "Yes."Since Trump's election on Tuesday night, the realities of actually building that wall have begun to set in. The Mexican government has publicly reminded him that Mexico will not pay for the wall. And asked about the wall, Trump transition co-chair Newt Gingrich said the wall was "a great campaign device." Trump also told "60 Minutes" that the border wall, which was one of the centerpieces of his campaign platform, could be part wall and "some fencing," in accordance with what congressional Republicans have proposed.