“On the domestic side, not so much,” he acknowledged.

The new Republican emphasis on foreign policy also has its practical value, providing a distraction from Republican failures on domestic policy.

It was hardly a coincidence that Speaker John A. Boehner informed House Republicans that they were unconditionally surrendering in their fight against Mr. Obama on immigration on the same morning that Mr. Netanyahu was to deliver a scorching reproach of the president from the House chamber. The prospect of the Israeli prime minister’s dressing down the president at the invitation of the speaker muted any backlash, and House conservatives went quickly and quietly.

Mr. Boehner has since invited the president of Ukraine, another place where congressional Republicans favor a more aggressive United States role than the White House does, to address Congress in September.

The foreign policy push against the administration has drawn many detractors among Democrats and even respected Republican foreign policy veterans.

They warn that lawmakers are treading into dangerous territory and setting precedents they may come to regret by first arranging the address by Mr. Netanyahu without informing the White House and then taking it upon themselves to write to Iran that any agreement with Mr. Obama might not hold up once he is gone.

Even some of the seven Senate Republicans who did not join their 47 colleagues in signing the letter despite their support of legislation requiring congressional review of any future nuclear deal suggested that it was ineffective and ill timed.

“I don’t think that the ayatollah is going to be particularly convinced by a letter from members of the Senate, even one signed by a number of my distinguished and high-ranking colleagues,” said Senator Susan Collins, Republican of Maine. She said the focus should be on “keeping the pressure on the president to make a good deal, not a bad agreement.”