Secretary of State John Kerry is under pressure to convince Congress to hold off on new sanctions legislation against Iran, as he prepares to testify Tuesday amid a renewed effort in the Senate to turn the screws on Tehran. 

A bipartisan group of senators is preparing to propose new sanctions against Iran. News reports on the bill prompted that country's foreign minister to warn such a step would kill the nuclear deal negotiated last month aimed at curbing Tehran's uranium enrichment program.

"The entire deal is dead," Iran Foreign Minister Javad Zarif told TIME Magazine in an interview conducted Saturday and published Monday. "We do not like to negotiate under duress. And if Congress adopts sanctions, it shows lack of seriousness and lack of a desire to achieve a resolution on the part of the United States."

The Obama administration is adamantly opposed to new legislation at this stage, and Kerry will likely try to persuade lawmakers to hold off, when he testifies Tuesday afternoon before the House Foreign Affairs Committee. 

The Senate group, led by Sens. Robert Menendez, D-N.J., and Mark Kirk, R-Ill., has agreed that the new sanctions would take effect in six months, when the current interim deal brokered between the U.S., Iran, and five other world powers expires, if a satisfactory long-term deal is not struck. The sanctions would permit Iran to develop nuclear power for commercial purposes, so long as the development is monitored by the international community. 

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"We'll do sanctions tied to the end game where the relief will only come if they stop the enrichment program, dismantle the reactor and turn over the enriched uranium," Senator Lindsey Graham, R-S.C., told CNN Monday. 

The senators hoped to announce the details of the proposed sanctions sometime Tuesday. 

State Department spokeswoman Jen Psaki said Monday that imposing new sanctions on Iran, even those that are delayed, would be counter productive and could "unravel the unity" of the six world powers working to implement the deal.

"It could certainly put the negotiations that we have all worked so hard on that we believe is the best chance we’ve had in a decade to achieve a peaceful outcome at risk,"  Psaki told reporters.

Psaki said Secretary of State John Kerry will make an appeal against passing new sanctions during a hearing Tuesday before the House Foreign Affairs Committee.

The United States and other Western powers suspect Iran's nuclear program is aimed at weapons development. Iran says it is for peaceful purposes like power generation, medicine and research.

Iran's President Hassan Rouhani on Sunday told an open session of parliament that, after the "success" of the nuclear talks, investors were gravitating to businesses and the stock exchange.

"Economic activities have been shifted to the stock exchange from gold, hard currency and real estate," said Rouhani in his televised speech. He gave no specific figures.

Iran's economy has been hit hard by sanctions imposed over its nuclear program. Rouhani has recently stressed the deal's offer of sanctions relief in return for a halt to parts of Iran's uranium enrichment program to challenge criticism from hard-liners who say Iran is giving up too much for too little.

The Obama administration estimates relief from some sanctions in exchange for a temporary pause in Iran's nuclear enrichment program will amount to just $7 billion, a meager amount for a nation of nearly 80 million people — it's less than one month's worth of Iran's oil production and just 7 percent of Iran's overseas cash that remains frozen under the sanctions.

The Associated Press contributed to this report.

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