(CNN) - The top Democrat and the top Republican on the House Foreign Affairs Committee were both skeptical Sunday of the interim deal reached to slow Iran's nuclear program in exchange for a loosening of sanctions against the country.
Rep. Eliot Engel, D-New York, said on CNN's "State of the Union" he was disappointed Iran will be allowed to continue to enrich uranium while the talks go on for the next six months.
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"I would have thought that that should be a prerequisite to any kind of talks - without asking them to dismantle any of their centrifuges. So that's disappointing," said Engel, the committee's ranking member.
The agreement requires Iran to dilute its stockpile of uranium, some of which had been enriched to 20%, to no higher than 5%, the level needed for nuclear power plants. Iran will also have to cut back on constructing new centrifuges and enrichment facilities, and freeze essential work on its heavy-water reactor under development at Arak.
"But the agreement is here. We have to make it work," Engel told CNN chief political correspondent Candy Crowley. "And I think we need to be very, very careful with the Iranians. I don't trust them. I don't think we should trust them. But I think that we have to make it work."
In July, Engel and the committee's chairman, Rep. Ed Royce, R-California, helped pass a bill in the House with overwhelming bipartisan support that broadened sanctions against Iran.
Engel said the new agreement "makes it very difficult to continue the sanctions."
"I think we could have played good cop, bad cop. And Congress really believes that sanctions should happen," he said.
"But I do think sanctions should always be hanging there because that's what brought Iran to the table in the first place," he added. "I don't think you make them bargain in good faith by going squishy."
Royce agreed, telling Crowley that sanctions are important as the talks continue over the next six months.
"You have to be able to hold their feet to the fire on these negotiations, because once before we had an agreement with Iran, they walked away from it. And the (International Atomic Energy Agency) had an agreement with Iran, and Iran went ahead and built an enriched facility building and lied to the IAEA about that," Royce said.
Royce also cautioned the loosening of sanctions will upset the balance of power among regimes in the Middle East.
"(Other regimes) feel in letting up on Iran and lifting sanctions, we're going to re-empower Iran to be the hegemon in the Middle East, to take that money and continue to support Hezbollah, Hamas, attempts to overthrow Saudi Arabia," he said, adding, "They are a state sponsor of terrorism, trying to get a bomb."
The deal says that the U.S. will provide $6 billion to $7 billion in sanction relief - a small fraction compared to the roughly $100 billion in foreign exchange holdings that are inaccessible to Iran because of sanctions, the White House says.
Secretary of State John Kerry argued the sanctions part of the agreement offers "very little relief" for Iran.
"The basic architecture of the sanctions is staying in place," he said on "State of the Union."
Kerry also hit back against criticism that the agreement failed to dismantle Iran's nuclear program.
"While we go through these next six months, we will be negotiating the dismantling," he said. "But you can't always start where you want to wind up."
"You cannot sit there and pretend that you're just going to get the thing you want, while they (Iran) continue to move towards the program that they've been chasing," he said.
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