New Jersey Gov. Chris Christie as he appeared on CNBC's "Squawk Box," Thursday, August 27, 2015.  Christie said on Saturday that if elected president, he would use a FedEx-like system to make sure visitors who enter the United States legally on visas depart the country when their time is up. He maintains that 40 percent of illegal immigrants with visas overstay their visits.  The governor, who is running well behind among the 17 contenders in the Republican White House race, sought to draw a distinction between his proposal and what he called Republican frontrunner Donald Trump's "simplistic" idea on how to deal with an estimated 11 million illegal immigrants in the United States.  Trump, who has a 21-point lead over his closest Republican rival, Mike Huckabee, according to a Reuters/Ipsos survey , has said he would deport undocumented immigrants and build a wall between the United States and Mexico.  Read MoreHas Donald Trump forced Jeb Bush to change his tune?  "I've put forward a much more detailed proposal than that," said Christie, adding that the presidential race was "not only about personality. It's also about ideas. And it's about who can get it done."  Christie has said he would ask FedEx Chief Executive Officer Fred Smith to devise the tracking system. A FedEx spokeswoman declined to comment on his remarks.  Trump's railing about illegal immigrants has prompted other Republicans to talk tougher on immigration but has also rattled Republican Party leaders who are desperate to attract support from Latino voters who have Democrat Hillary Clinton's pledge to seek citizenship for illegal immigrants if elected in 2016.  On NBC's "Meet the Press" program, Wisconsin Governor Scott Walker said he would be open to building a wall along the U.S. border with Canada—not just the southern border with Mexico.  "Some people have asked us about that in New Hampshire. They raised some very legitimate concerns, including some law enforcement folks that brought that up to me at one of our town hall meetings about a week and a half ago. So that is a legitimate issue for us to look at," he said.
New Jersey Governor Chris Christie pushed back against "ridiculous" criticism of his proposal to track foreign visitors the way FedEx tracks packages.