Trump at a Tea Party rally against the Iran nuclear deal
Trump at a Tea Party rally against the Iran nuclear dealReuters

Republican presidential challengers Donald Trump and Senator Ted Cruz joined forces on Wednesday at a rally denouncing the Iran nuclear deal being debated by the United States Congress, AFP reported.

Thousands of people converged on the West lawn of the Capitol to hear the two Republican powerhouses and to protest President Barack Obama's landmark accord with Iran, saying the international agreement could mark a death knell for Israel and threaten the lives of millions of Americans.

Trump, the billionaire real estate tycoon and Republican frontrunner, blasted the "incompetently negotiated" deal and criticized the Obama administration for failing to include the return of four Americans held in Iran as part of the negotiation.

"If I win the presidency, I guarantee you that those four prisoners are back in our country before I ever take office," Trump boomed, to raucous applause, according to AFP.

"We are a country that owes $19 trillion," Trump added. We lose everywhere," he added, departing from the Iran rhetoric to repeat his claims that as a world-class negotiator he would get America back on the winning track.

"We will have so much winning if I get elected that you may get bored with winning," he said.

Cruz also received a hero's welcome from the crowd, which was aligned with the conservative grass roots Tea Party movement that helped propel Cruz to victory in his 2012 Senate race.

"If you vote to send billions of dollars to jihadists who have pledged to murder Americans, then you bear direct responsibility for the murders carried out with the dollars you have given them," Cruz said of Democrats supporting the agreement, referring to frozen funds that would return to Iran when sanctions are lifted.

"You cannot wash your hands of that blood," declared Cruz.

Meanwhile, a separate rally took place nearby, attended by some 200 rabbis from the Orthodox Union (OU) and the Rabbinical Council of America (RCA) who gathered to warn against the nuclear deal and the threats it poses.

Despite the heated opposition outside the Capitol, and the ongoing debate inside, the Iran deal has sufficient support to go ahead.

42 Senate Democrats are in favor, more than enough to block aresolution of disapproval against the deal in the 100-member Senate. All Republicans stand opposed.

Rally protesters held up signs attacking Democrats for supporting the controversial accord, which is aimed at rolling back Iran's nuclear program in exchange for an easing of punishing economic sanctions.

"What part of death to America, death to Israel don't you understand?" one sign read.

"Anybody who votes for this deal hates America and wants her to go down in flames," Jim Griffin, a protester dressed in a Captain America outfit and waving a large American flag, told AFP.

AFP contributed to this report.