From Scott Johnson:

John McCain seems rarely to differentiate issues of constitutional principle from issues of practical politics. He is unbending both when he is right and when he is wrong on these issues. To say that McCain is not a party man does not do justice to the case; he tends to subsume practical political questions into matters of personal honor, and occasionally to miss applicable constitutional principles in the process. One might call the tendency Caesarist, except that Senator McCain apparently aspires to be seen exceeding the purity of Caesar’s wife.