Senator Ron Johnson said he hoped President Trump was making empty threats, but most in the G.O.P. cheered his warning that Iran’s “whole civilization” would be wiped out.

G.O.P. lawmakers who have given the Trump administration wide latitude to wage war with no congressional input are growing frustrated as officials offer little detail about ground troops, cost or timeline.

Nearly every Republican voted to block a measure that would require that President Trump win authorization from Congress to continue the offensive in the Middle East.