More than 100 miles north of the U.S.-Mexico border, Interstate 8 runs through the mostly untouched Sonoran Desert National Monument. Back in 2010, in addition to cacti, flowers and three distinct mountain ranges, motorists traveling along I-8 also saw signs posted by the Bureau of Land Management, informing them that they had entered an "active drug smuggling area" and might encounter "armed criminals and smuggling vehicles traveling at high rates of speed."

"Mexican drug cartels literally do control parts of Arizona," Pinal County Sheriff Paul Babeu told reporters at the time. "They literally have scouts on the high points in the mountains and in the hills and they literally control movement."

FBI statistics show that violent crime is down since 2010 in border urban areas like Tucson, Arizona, and El Paso, Texas. But even 100 miles from the border, in rural areas like the Sonoran Desert, the federal government still felt the need to post signs informing visitors that their national parks are too dangerous to visit. This should not be.

National security is the primary function of the federal government. Congress and the White House must do what it takes to secure the nation's borders -- and they must do so irrespective of any other issue, including the entirely unrelated matter of immigration reform.

We believe that Congress must reform the immigration system. We support conferring some legal status on illegals who are living in the shadows, putting an end to their legal limbo. We also support higher levels of legal immigration, especially for high-skilled foreign workers and those who earn advanced degrees in the United States. But these issues have nothing to do with safety concerns at the border. The safety of Americans from foreign drug armies is not a bargaining chip to be used to win concessions in a political deal. Especially now that the tide of immigration from Mexico has slowed so dramatically, there is no sense in treating these two issues as if they were one.

Unfortunately, many politicians don't seem to view it this way. On Monday, a bipartisan group of eight senators (Sens. Chuck Schumer, D-N.Y., Robert Menendez, D-N.J., Michael Bennet, D-Colo., Dick Durbin, D-Ill., Marco Rubio, R-Fla., John McCain, R-Ariz., Jeff Flake, R-Ariz., and Lindsey Graham, R-S.C.) released an immigration reform plan that explicitly ties achieving border security with providing a "path to citizenship" to the 11 million people currently living in the U.S. illegally.

As NBC News' Chuck Todd explained, "Despite all this talk that nothing comprehensive can get done anymore, Rubio and McCain are saying that this has to be comprehensive -- 'we're never going to get border security without the pathway to citizenship.' " This is not true, nor is the reverse true.

If lawmakers take their oaths seriously, they will deal with border security on its own merits, simply because it is their grave constitutional duty. They will then discuss immigration reform on its own merits, because it's the right thing to do. The nation -- including the political Right -- has never been as amenable to the idea of immigration reform as it is now. Lawmakers may find that reform proposals get a lot more support than they expect.