Top State Department official Wendy Sherman told Congress that President Obama's public position on the Iranian nuclear program is a "maximalist" starting point for negotiations with the regime.

"A negotiation begins with everybody having their maximalist positions," Sherman, the undersecretary for political affairs, told Sen. Marco Rubio, R-Fla., while discussing the Iranian and American demands.

"And we have ours, too, which is they have to meet all of their obligations under the NPT and the UN Security Council resolutions. And they have their maximalist positions. And then you begin a negotiation."

Moments earlier, she noted that "President Rouhani actually qualified his own statement. He said we will not give up our capability to have enrichment, but we can discuss the details."

Rubio asked Sherman if there was a scenario in which Obama would agree to ease sanctions on Iran if that country's regime doesn't give up its efforts to enrich weapons-grade uranium.

"I’m not going to negotiate in public, Senator, with all due respect," Sherman replied. "All I can do is repeat what the President of the United States has said, which is, 'We respect the right of the Iranian people to access peaceful nuclear energy, in the context of Iran meeting its obligation. The tests will be meaningful, transparent and verifiable actions.'"

She reiterated that "Iran must meet the concerns of the international community, including the United States, and all of its obligations under the [Non-Proliferation Treaty] and the UN Security Council resolutions, which has suspended its enrichment."