Janus was the Roman god of gates, doors, borders, and, of course, giant electric barbwire-laden fences. He also aptly symbolized the change from past to future, and was himself the border between the progression of one vision to another. On immigration, the Republicans' varying opinions of either procedural or literal gates and walls has highlighted a similar border within the party: between progressive and retroactive visions. Some are looking sensibly forward, others obstinately backward. Janus did, after all, symbolize the convergence and separation of barbarity and civilization.
On that note, I am quite proud to be in the Colorado Congressional district of Tom Tancredo (remember, the "nuke Mecca" guy?), who has long been the staunchest opponent of immigration. His rhetoric often takes a scary turn toward "preserving American (read, white) culture." Read more about Tancredo and the various opinions regarding immigration at Mother Jones.