In a tweet this morning, NBC News senior political editor Mark Murray writes: “With GOP Senators’ Iran Move, Politics Goes Beyond the Water’s Edge.” 47 Republican Senators sent to the Supreme Leader of Iran reminding him that Congress is not bound by deals that Congress does not approve. The article Murray links to describes this as “stunning” and “unprecedented” and implies that the letter constitutes a breach of protocol so significant that it ends the long tradition of bipartisan foreign policy. This is utterly preposterous. The only way to reach such a conclusion is to ignore efforts by Democrats to...