There is nothing realist about an ideology that declare ideology irrelevent. And there is nothing realist about allowing Iran to have nukes. It’s suicide by cowardice.
And Realism is used as an opposition to Idealism. The Liberal Interventionists and NeoCons are Idealists. The idealists advocate for a foreign policy that includes humanitarianism, nation building, and spreading democracy but the Realists say only what is in the US interests. So the Idealists say we should go after Assad in Syria for idealistic reasons but the Realists say only if that is in our best interest. And sometimes the Realists advocate for making a deal with an evil, despotic national leader like Pinochet, in which case it is said that the Realists are Machiavellian.
In the GOP there are Realists, NeoCons, and Isolationists. In the dem party there are Realists, Liberal Interventionists, and Antiwar Pacifists. The vast majority of Careerists(military, State dept, intelligence) are Realists.
A repubilican prez's foreign policy team will always be made up of Realists and NeoCons. A dem prez's foreign policy team will always be made up of Realists and Liberal Interventionists.