mellow
同じく先程と同じニュースからです。
mellowは「熟す」でお馴染みかと思いますが赤字の部分は「円くなる(+out)」（『ジーニアス英和辞典 第3版』大修館）に相当します。しかしながらも、本文では「穏やかになった」あるいは「和やかになった」と意訳できますでしょうか。（Shou-VR*）
Schumer Offers Long-Shot Option to Skirt House G.O.P. on Immigration
Even Democratic lawmakers and aides eager to see an immigration overhaul before the end of the year privately say that the path forward is still through Mr. Boehner; they are hoping that now that the potential debt ceiling crisis is out of the way, the House Republican leadership will return to the question of immigration once the mood has mellowed slightly.
