Idaho residents and political leaders, finding themselves in the spotlight, have reacted with anger and fear that children might pay the price, but also in some cases with a kind of prickly pride. Idaho, in the face of what felt to some legislators on the committee like bullying from the federal government, had hit right back.

To Ryan Kerby, a Republican and first-term state representative, a good part of his vote came down to simple courtesy. He was not, he said, about to be told what to do by mostly nameless federal officials who had communicated their demands to the state, and then would not grant legislators more time to think about it.

“You need to sign it, and if you don’t we’re going to beat the crud out of you,” Mr. Kerby said, paraphrasing the pressure he felt. “They were incredibly rude.”

Idaho’s governor, C. L. (Butch) Otter, a Republican, will almost certainly have to call the Legislature into a special session if the bill and the treaty questions are to be addressed again, legal experts said. Mr. Otter said at a news conference on Thursday that he was not prepared to do that yet.

Other Idahoans are just scratching their heads. The child support bill, through most of the legislative session leading to the committee’s vote, had drawn little attention or controversy. The Senate passed it unanimously.

“It’s an interesting issue because no one, even those in the room, seems to understand exactly what happened, and the long-term implications are so unclear,” said Shaakirrah R. Sanders, an associate law professor at the University of Idaho.