What the opponents of a bad deal with Iran have witnessed over the last few months is the transference of Obama’s domestic political strategies to the international stage. A senior administration official is on record likening an Iranian nuclear agreement to Obamacare, and the comparison makes sense not only in the relative importance of the two policies to this president, not only because both policies are terrible and carry within them unforeseen consequences that will not be manifest for years, but also because of the way opponents of both policies are treated by the White House. If they are not ignored or dismissed, their motives are impugned. They are attacked personally, bullied, made examples of.
UPDATE: See also "Obama’s Failure".