Security along the U.S. border with Mexico is perhaps the key factor in the debate over comprehensive immigration reform. Those who believe the border is mostly secure already are more inclined to support the plan of the bipartisan Gang of Eight in the Senate -- legalization first, followed by enhanced security. Those who believe the border is still far from secure are more likely to oppose the Gang of Eight's approach, insisting heightened security is in place before the nation's estimated 11 million illegal immigrants are legalized.Now, a new report from the Council on Foreign Relations could have a significant effect on the conversation -- and cast real doubt on whether the government's border security statistics are reliable.