Iranian Foreign Minister Mohammad Javad Zarif (center) and the head of Iran’s Atomic Energy Organization Ali Akbar Salehi (left) arrive at Tehran’s Mehrabad Airport on Wednesday, after striking a deal with world powers in Vienna.

Under the agreement, sanctions imposed by the USA, the European Union and the United Nations would be lifted in return for Iran agreeing long-term curbs on a nuclear program that the West has suspected was aimed at creating a nuclear bomb. A congressional defeat of the accord would only maintain sanctions put in place by Congress. “[I]f somebody wants to make that debate, whether it’s the Republican leadership, or [Israeli] Prime Minister [Benjamin] Netanyahu, or the Israeli ambassador or others, they’re free to make it. But it’s not persuasive”, Obama said.

But he acknowledged that although he hopes the global deal will encourage Iran to rein in its aggressive conduct in the region, he was not betting on a change.

He said Israel was not bound by the deal – struck by America, the United Kingdom, Russia, China, France and Germany – and that “we reserve our right to defend ourselves against all of our enemies”.

“Congress should reject this agreement, and urge the administration to work with our allies to maintain economic pressure on Iran while offering to negotiate a better deal that will truly close off all Iranian paths to a nuclear weapon”.

“What I haven’t heard is: what is your preferred alternative”, Obama told critics during a White House news conference.

Obama has said he will veto any “resolution of disapproval” if it is passed by Congress. Passage of such a resolution would cripple the agreement, reached by six major powers and Iran, by barring Obama from waiving most USA sanctions on Tehran. “We’re not measuring this deal by whether we are solving every problem that can be traced back to Iran, whether we are eliminating all their nefarious activities around the globe”.

Saudi Arabia is both a longtime American ally and, by far, the most important of the Arab monarchies and sheikdoms that lie just across the Persian Gulf from Iran.

Vice President Joe Biden, who on Wednesday met privately with Democrats from the House of Representatives, returned Thursday to Capitol Hill to hold similar talks with Democrats on the Senate’s Foreign Relations Committee.

New Jersey Governor and Republican presidential candidate Chris Christie accused President Barack Obama of telling “lies” about the Iran nuclear deal. Republicans could prevent the lifting of sanctions, but Obama could veto them.