WASHINGTON — Senator Bob Corker, Republican of Tennessee and the chairman of the Foreign Relations Committee, stared at Secretary of State John Kerry on Thursday with thinly veiled disgust.

“You have turned Iran from being a pariah to now, Congress being a pariah,” said Mr. Corker, who helped broker a delicate deal with Democrats and the White House allowing lawmakers to review the proposed lifting of sanctions against Iran.

While Mr. Corker, who promised a considered assessment of the agreement, may have seemed close to an endgame during a hearing on Capitol Hill, the vast majority of Republicans appear to have made up their minds before a single classified briefing, hearing or visit with administration officials.

Their view seems born of genuine distaste for the deal’s details, inherent distrust of President Obama, intense loyalty to Israel and an expansive view of the role that sanctions have played beyond preventing Iran’s nuclear abilities.