By THE EDITORIAL BOARD

The bruising battle over the Iran nuclear agreement should be over, now that 42 Democratic senators declared their support for the deal and made it clearer than ever that efforts to kill it will fail. But the Republican-led Congress seems determined to drag out the fight, even if it means neglecting other business, including legislation to fund the government.

Of course, the Republicans don’t much care about governing or putting in place the protections needed to make sure the nuclear agreement, reached in July between Iran and six major powers, is carefully and strongly enforced. This would include providing full funding for the International Atomic Energy Agency, which will play a crucial role in inspecting and monitoring compliance with the pact.

Instead, the Republicans, who unanimously oppose the agreement, on Wednesday signaled their intent to keep fighting, at least until Sept. 17, the deadline for action set by Congress when it passed legislation in May giving it a say in approving or disapproving the accord. If lawmakers do nothing by next Thursday, the deal goes into effect.

The debate has been vitriolic and raw, with opponents waging a multimillion-dollar campaign that relied heavily on distortions and made supporters of the strong and worthy deal out to be anti-Israel or worse.

Now, with 42 Democratic senators declaring their support for the accord, there is no way for the opponents to muster 60 votes to defeat a Democratic filibuster against the resolution of disapproval, should it come to that.

On Wednesday, the House postponed its debate on the accord after some Republicans revolted, arguing the White House had not disclosed “secret side agreements” between Iran and the international nuclear agency, which have to do with questions about past Iranian nuclear research at a military facility called Parchin. Activities at the Parchin facility ended years ago; lawmakers have been briefed on the details, but are not allowed to see documents related to this issue, which are confidential between Iran and the nuclear agency.

House Republicans might be considering some legal tactic to hold the administration in violation of the law that set out procedures for voting on the nuclear deal. That may endear them to opponents of the deal, including Prime Minister Benjamin Netanyahu of Israel and the American-Israel Public Affairs Committee, who invested considerable political capital in trying to kill it. But there seems no way that a delay in congressional action will change the result: the agreement will take effect.

As with any agreement, there will be pitfalls ahead. Iran may try to cheat. Congressional opponents undoubtedly will try to devise schemes that could sabotage the deal by indirect means, including by voting new sanctions to replace the ones the agreement would lift.

Iran’s supreme leader, Ayatollah Ali Khamenei, who allowed the deal to go forward, on Wednesday gave its opponents more ammunition — in remarks on his website and in posts on Twitter, he predicted Israel will not exist in 25 years and ruled out new negotiations with the United States, the “Satan.” His contempt is well known, but it should not drive an analysis of whether the multinational pact that constrains Iran’s nuclear activity improves regional security, which it does.

Making sure the agreement is stringently enforced will be the responsibility of Mr. Obama, but the future is in the hands of his successor. Some of the Republican presidential contenders were outside the Capitol on Wednesday at an anti-accord rally, offering bogus denunciations of the deal.

Hillary Rodham Clinton, the Democratic front-runner, delivered a detailed speech outlining her “distrust and verify” approach for implementing the deal, which she supports. And she called for a broader strategy that includes plans for a stepped-up effort to contain Iran’s military activity and increased military support for Israel. That is the responsible way forward.