President Barack Obama has secured another significant political victory, securing 34 votes in the Senate in support of his nuclear deal with Iran, insuring it can survive attempts by congressional Republicans to sink it.
Senate Republicans, who hold a majority, plan to hold a vote of disapproval for the deal by September 17. But the President now has the numbers to veto any such vote.
The politics surrounding the deal in the United States has been vicious over the northern summer, and it has come to be viewed as an measure of Mr Obama's authority as he enters what should be the lame duck phase of his presidency.
Opponents of the deal have accused the administration and its supporters of creating a legal pathway for Iran to obtain a nuclear weapon.
Those in favour of the deal have accused their opponents of of paving the way to war with Iran, and of ignoring the will of America's negotiating allies.
"Many of the same people who argued for the war in Iraq are now making the case against the Iran nuclear deal," Mr Obama said in speech on August 5. "The choice we face is ultimately between diplomacy or some form of war."
The administration's victory also marks a rare defeat for the Israeli lobby and its allies among hawkish Republican neoconservatives.
The lead negotiator, US Secretary of State, John Kerry, told CNN the administration would seek to win even more support before any congressional vote is held.
The 34th senator to come out in support of the administration was the Democrat Barbara Mikulski, who said in a statement on Tuesday, "No deal is perfect, especially one negotiated with the Iranian regime.
"I have concluded that this Joint Comprehensive Plan of Action is the best option available to block Iran from having a nuclear bomb. For these reasons, I will vote in favour of this deal."
Only two Democratic senators, Charles Schumer, of New York, and Robert Menendez, of New Jersey, have announced their opposition to the deal, even as opponents spent millions of dollars lobbying Democrats in Congress.
Israeli Prime Minister Benjamin Netanyahu, who personally lobbied American legislators against the deal, has vowed to continue his opposition.
Though it now appears certain the deal will survive any legislative moves to kill it, it will remain a heated political issue in American politics, as Republican presidential candidates use it to signpost their conservative credentials.
Primary candidate Donald Trump, the real estate mogul who is leading in the polls, will appear with Senator Ted Cruz, the Tea Party champion, in a rally opposing the deal in Washington, DC, next week.
Senator Marco Rubio, of Florida, another contender, has declared, "When I'm president, we won't just reverse President Obama's dangerous Iran deal. We will increase sanctions on Iran."
The United Nations Security Council in July unanimously endorsed the Iran nuclear deal, negotiated by the United States, China, Russia, Britain and France.
Republicans have not made it clear how they would maintain sanctions without the support of those nations.
