With support waning for Iran sanctions legislation, top US Iran negotiator Wendy Sherman and Treasury Undersecretary David Cohen testified on the Iran nuclear deal to the Senate foreign relations panel Tuesday.

Despite sinking prospects for the Iran sanctions bill he co-sponsored, Senate Foreign Relations Committee chair Robert Menendez (D-NJ) expressed continued deep skepticism about the terms of the interim Iran nuclear deal which went into effect on Jan. 20, and to be looking for ways to constrain the administration’s hand for negotiating a comprehensive Iran nuclear deal.

But the nitpicking, somewhat sour tone of the hearing was broken by Sen. Tim Kaine (D-Virginia), who made an impassioned case for aggressive US diplomacy with Iran, while defending colleagues who supported the Iran sanctions legislation from charges of war-mongering.

“We have to be able to look allies and citizens & [US service members] in the eye and tell them we exhausted every diplomatic effort,” Kaine told the hearing. “We have got to give diplomacy a chance. …. We have to return to the tradition of aggressive diplomacy.”