Nearly three weeks into a war that polls show is unpopular, top Republicans have yet to call administration officials to testify about it, arguing that hearings would put divisions on display.
Republicans on Capitol Hill have given President Trump wide latitude to wage war on Iran with no congressional approval or limits.
They have deferred to him almost entirely on his justifications for the conflict, echoing the rationales offered by him and his top officials, even as they have given shifting and contradictory explanations.
Now, nearly three weeks after the first strikes on Tehran, G.O.P. lawmakers are resisting the idea of calling top administration officials before Congress to give a public accounting for an escalating war with uncertain objectives, a rising price tag and no clear exit strategy.
It is the latest example of how the Republicans controlling Congress, who have ceded power to Mr. Trump on matters large and small, are refraining from using their oversight authority as a coequal branch of government and have instead taken on the role of cheerleaders for his policies at a critical time.
“You don’t want to show that kind of division to your enemy when you’re in the midst of a war,” said Senator Ron Johnson, Republican of Wisconsin. “I don’t have a problem with the administration avoiding showing our enemy that they don’t have 100 percent support of the Congress.”