Tom Cotton made his name in Washington as an outspoken critic of a Democratic president's deal to check Iran's nuclear ambitions.

Now, with a president of his own party angling toward a similarly structured agreement, the Arkansas Republican is so far using a softer voice.

Cotton, the No. 3 Senate Republican and Intelligence Committee chair, is not alone among GOP defense hawks in finding himself in an awkward position more than a decade after lambasting President Barack Obama's Iran deal.