USA officials told CNN Trump was moving forward with his decision despite the assessment by the worldwide community, which said Iran was maintaining its condtions under the Joint Comprehensive Plan of Action (JCPOA) agreement. Secretary of State Rex Tillerson and U.S. Ambassador to the U.N. Nikki Haley have said the U.S. interprets the agreement differently than the other countries involved.
Yet Iran's semi-official Fars News Agency reported Wednesday that the country's foreign minister said Tehran "will never" renegotiate the deal. Joined by several Democrats, they almost passed legislation to kill the deal in which Iran agreed to curb its disputed nuclear program in exchange for sanctions relief.
Democratic leader Nancy Pelosi cautioned against leaving the Iranian nuclear agreement, which was one of the top foreign policy achievement of the former president Barack Obama.
She said that USA would lose global trust "because a deal that America voted for just two years ago in the UN Security Council with a resolution unanimously adopted, a deal that America helped to shape enormously, enormously, would be rejected by the same country".
In exchange, UN, US and European Union sanctions were to be gradually removed from Iran.
Mogherini pointed to other worldwide agreements that the United States has abandoned but the rest of the world has remained committed to, including the Paris Agreement on climate change.
A Twitter feud that erupted this week between Trump and Corker could complicate the efforts by the influential Republican to broker a deal that would likely require both Democratic and Republican support.
If Trump does decertify the accord as expected, it would put him at odds with Defense Secretary James Mattis, who last week said Tehran was "fundamentally" in compliance with the agreement and that the USA should stick with the pact.
Officials familiar with the internal deliberations as well as informed sources outside the administration say they do not believe Trump will call for Congress to reinstate the sanctions.
"I expect President Trump will not certify it", said Elizabeth Rosenberg, an Iran expert at the Center for a New American Security, a progressive think tank.
Trump, who has been sharply critical of Iran and accused Tehran of working with North Korea on lethal weapons, faces an October 15 deadline on whether to certify to Congress that Iran is compliance with the terms of the nuclear agreement. "We may have to array our forces to prepare for. calibrated strikes".
"If we withdraw from the deal now, Iran would be free today from the constraints on their program and the intrusive inspections that the JCPOA puts into place", he said.
Watch Federica Mogherini's full interview with the NewsHour's Judy Woodruff on Wednesday.
Why does U.S. President Donald Trump want to scrap it? She said, "It is not a deal you can easily open and renegotiate".
In this environment, many Democrats believe working on the periphery of the deal could be the congressional equivalent of destroying the village to save it.
As British Ambassador to the U.S. Kim Darroch said on September 25, "We would say, let's intensify the discussions [on how to deal with Iran's other activity], but let's keep the JCPOA".
European officials expressed relief that the White House speech did not appear to represent an United States abrogation of the 2015 deal, which they had intensively lobbied against since it became clear over recent months that Trump did not want to continue to certify the deal to Congress.