The Obama administration has said consistently for two years that it wants to reach an agreement that ensures Iran's nuclear program remains peaceful and can never be used to develop a nuclear weapon.

But the administration has made a series of concessions, almost from the start, that have the potential to thwart the basic goal of the talks, even if an agreement is reached. Those concessions have contributed to a wide gap in public opinion, with majorities of voters telling pollsters they support the idea of reaching a deal but are also skeptical that any agreement will meet its goal. This view is reflected in the concerns of a bipartisan majority of lawmakers.

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"The administration's deadlines and redlines with Iran are all moving in the wrong direction, and the backpedaling is a major threat to our security. Achieving a nuclear deal at all costs is not only short-sighted, it is dangerous," House Armed Services Chairman Mac Thornberry, R-Texas, said Wednesday.