"There's so much mistrust, of course, that we bring to these negotiations after generations of suspicion and that cuts both ways," she said. "With the temporary, modest, reversible, limited relief that we're promising here, in return, we freeze the program, they dilute some of the highly-enriched uranium, and we get a much more aggressive inspection verification regime."
She added, "To think that we could go from zero to 60 overnight and come to Congress with a comprehensive deal, that any of us would trust, having not probed it in this way, I think, is not realistic."
President Obama is asking Congress not to approve new sanctions against Iran in the middle of negotiations over Tehran's nuclear program.
He said Thursday, "If we're serious about pursuing diplomacy, then there's no need for us to add new sanctions on top of the sanctions that are already very effective, and that brought them to the table in the first place. Now, if it turns out they can't deliver, they can't come to the table in a serious way and get this issue resolved, the sanctions can be ramped back up and we've got that -- we've got that option."
Throughout the negotiations, protests have continued in Israel and warnings have been issued by Prime Minister Benjamin Netanyahu about Iran. Responding to a question about whether that has made negotiations more difficult, Power said, "Israel has been a great partner with us throughout this process. Our goals are identical, which is to prevent Iran from getting a nuclear weapon, and we're going to continue to consult closely with them. When the talks resume, we're hopeful that we can get an interim arrangement that does a lot more good and could give us more confidence at the end of six months."
She also said, "The sign that this is not a good deal for Iran, is the fact that they haven't taken the deal that's on the table right now."
Power said the U.S. was concerned about not doing an interim deal with Iran. "We were concerned...they'd be taking advantage of the length of the negotiation. So again, a feature of this is much more aggressive verification, inspection. And the IAEA (International Atomic Energy Agency) report that we got yesterday, which we're still reviewing, shows actually since Rouhani came to power, the program has been frozen, at least from the IAEA perspective."
Turning to Syria, Power said there has been "very significant progress" in the first phase of chemical weapons disarmament, noting that delivery systems are beginning to be destroyed.
"Now we're moving into the most challenging phase, destroying of the (chemical weapons), either in Syria or moving it out of the country, which, I think, is our preference for much of the material," she said.
And all of this, Power said, in the midst of "blazing inferno" of a civil war. "Hats off to the (United Nations) and the (Organization for the Prohibition of Chemical Weapons) putting their people in harm's way trying to conduct this mission.
"On the political, things are not as promising," she continued. "We are seeking, though, to bring the parties together as soon as we can. The opposition has sent some encouraging signs in the last few days, but what is needed, of course, is a transitional governing body that is agreed upon by mutual consent."
She said parties are still pretty far apart, but, added the U.S. and Russia are "trying to do on the political side what we did on chemical weapons."
"CTM" co-host Charlie Rose said, "Our position is that (President Bashar Assad) cannot stay?"
"Oh, yes," Power said. "That's our position, not after you gas 1,000 people."
Power also addressed the U.N. Disability Treaty, which the U.S. has failed to join. She said she's hopeful that will change as the treaty is back before the Senate in a few months.
Looking back at when it was last up for consideration, Power said, "Last year, Senator Dole went door to door, actually sending notes from Walter Reed Hospital trying to get the Senate to sign on to it. And I think partly, it came up during the lameduck of the Congress, and there was some skepticism that was a good time to do a treaty. Partly, I think there was a lot of misinformation out there about what the treaty would do, what it would do is extend the rights that persons with disabilities at home enjoy, so that when they travel, work and live abroad, that those rights would extend to them."
She added, "It puts us party to a treaty that we then can use with other countries to get them to up their game. Right now, it's no secret we're the gold standard on disability rights in this country, which matters for our wounded warriors and again for other Americans with disabilities, but other countries don't have the same protections in place so this would give us the power to push this agenda."
For more with Power, watch her full interview above.