Businessman Donald Trump teamed up with fellow Republican presidential hopeful Texas Senator Ted Cruz and other major conservative figures at the U.S. Capitol for the "Stop the Iran Nuclear Deal Rally" Wednesday afternoon.
Trump blasted the administration's efforts, saying, "Never ever, ever in my life have I seen a deal so incompetently negotiated as our deal with Iran. ... We are led by very, very stupid people. We cannot let it continue."
Earlier in the day Democratic presidential candidate Hillary Clinton said, if elected, she would impose penalties on Iran for even small violations of the nuclear deal and "not hesitate" to take military action if Tehran tried to obtain a nuclear weapon.
"We should anticipate that Iran will test the next president. They'll want to see how far they can bend the rules," she said Wednesday in a speech at the Brookings Institution, a Washington research organization.
The dueling campaign events underscore the deep political divide over the Iran agreement, which was reached in July and will provide Iran hundreds of billions of dollars in relief from international sanctions in exchange for a decade of constraints on Iran's nuclear program.
Iran has repeatedly said their nuclear program is for peaceful purposes.
The deal is opposed by every Republican presidential candidate, but supported by most of the major Democratic presidential hopefuls.
Clinton's remarks appear to go a step further than President Barack Obama, who has repeatedly vowed that a military option remains on the table if Iran does not abide by the deal.
"I'll hold the line against Iranian noncompliance," Clinton said.
Former Secretary of State and Democratic presidential candidate Hillary Clinton speaks about the Iran nuclear agreement at the Brookings Institute in Washington, D.C., Sept. 9, 2015.
Speaking in defense of the deal negotiated by the U.S. and five other world powers, she said she would warn Iran: "The United States will never allow you to acquire a nuclear weapon."
Now that the nuclear deal appears able to withstand a congressional challenge, Clinton said, “We’ve got to start looking forward to what comes next ... enforcing the deal.
"We will take seriously every aspect of this agreement and we will expect them [Iran] to comply," she added
Clinton supports the Iran deal as the "best alternative" to another U.S. war in the region.
"Either we move forward on the path of diplomacy and block Iran's path to nuclear weapons or we turn down a more dangerous path, leading to a far less certain and riskier future," she said.
She has also made clear that, if elected, she would take a tough stance against Tehran regarding the agreement, and would "not hesitate" to take military action if Iran attempts to obtain a nuclear weapon.
As thousands gathered outside the Capitol Wednesday for the Trump-Cruz rally, U.S. lawmakers resumed debate on the agreement, a day after 42 Senate Democrats said they would support the deal. That is enough to prevent a disapproval resolution from being passed in the Senate.
Securing the votes means Obama will not likely be forced to follow through on his threat to use a veto against any resolution of disapproval of the deal.
Supporters wait for a rally against the Iran nuclear deal to begin, Sept. 9, 2015.
Cruz predicted the murder of “countless” Americans and Israelis should the proposed nuclear agreement with Iran go through.
He told the crowd that the Democrats who now support the Iran nuclear deal “should pray and think very carefully about how they will answer the questions that come from the mother or father or son or daughter of the countless Americans and Europeans and Israelis that will be murdered by Hamas, by Hezbollah, by the Houthis, with the billions of dollars this administration is sending them.”
Earlier inside the Capitol, Cruz told reporters, “If you are directly responsible for sending billions of dollars to jihadists who use those billions to murder Americans, you can't wash your hands of that blood.”
In response to the rally outside the Capitol, Dick Durbin, the No. 2 Democrat in the Senate, said: "The other side can roll out their big guns on this if they wish, but frankly I think most members of the Senate Democratic Caucus are not going to be swayed by Mr. Trump, our colleague, Senator Cruz, or even a former vice president."
Former Vice President Dick Cheney called the deal "madness" in an interview published Tuesday in The New York Times.
FILE - In this picture released by the official website of the office of the Iranian supreme leader, Supreme Leader Ayatollah Ali Khamenei delivers a speech during a meeting in Tehran, Aug. 17, 2015.
Earlier Wednesday, Iran Supreme Leader Ayatollah Ali Khamenei said any future talks with the U.S. will only deal with issues related to the nuclear deal reached with world powers, and not any other areas.
In a statement on his website, Khamenei said, "We approved talks with the United States about nuclear issues specifically. In other areas, we did not and will not allow negotiations with the U.S."
Negotiations on other issues would only provide an opportunity for the U.S. to "influence Iran and impose their will," the ayatollah was quoted as saying.
Iranian President Hassan Rouhani, who is seen as a moderate in comparison to the ayatollah, said Tuesday that Tehran was ready to hold talks with the U.S. on ways to resolve Syria's civil war.
Khamenei's comments on Wednesday are seen as a possible response to that comment.
William Gallo contributed to this report. Some material for this report came from AP and Reuters.