US Speaker of the House John Boehner vowed to "do everything possible" to stop the deal between Iran and nuclear powers from being approved by Congress, he said during a press briefing Wednesday.
"While the president's Iran deal may have been applauded at the United Nations, I think he faces serious skepticism here at home," Boehner asserted.
"Members of Congress will ask much tougher questions this afternoon when we meet with the president's team, and because a bad deal threatens the security of the American people, we're going to do everything possible to stop it," he added.
Boehner's assurance follows vocal responses from some American lawmakers, particularly Republicans, who have expressed their objection to the Iran deal.
A Republican Senator in the Senate Foreign Relations Committee made clear last week that American legislators are considering imposing further sanctions on Iran, despite the agreement.
President Barack Obama, however, has threatened recently to "veto any legislation" passed by Congress blocking the deal.
A law signed by Obama in May gives Congress the power to review and potentially reject a nuclear deal with Iran, but in spite of his willingness to allow Congress to debate the agreement, Obama has asserted it would be "irresponsible" to object to the deal.