Secretary of State John Kerry has sent a nearly eight-minute video message to Congress explaining America's recent deal with Iran.

Kerry spends most of the seven minutes and 42 seconds outlining the terms of the agreement reached over the weekend in Geneva between Iran and the U.S., U.K., France, Germany, Russia, China and the European Union to suspend Iran's nuclear program for six months and roll back about $7 billion worth of international economic sanctions over the same time period.

But he also explains the science. Speaking slowly and sounding a bit like the narrator of an educational video shown to physics or chemistry students, Kerry walks Congress through some basics on nuclear energy and uranium enrichment.

"Uranium, as I'm sure you know, is found in nature, but it's found in a form, a raw form, that can't be used for a bomb," Kerry explains. And: "Plutonium, on the other hand, is not found in nature. It requires putting uranium into a reactor and then you separate out the plutonium from the uranium. Our proposal addresses both of these paths to nuclear weapons." One congressional office confirmed it has seen the video.

Congressional action threatens to undermine the Iran deal. The Senate will examine new sanctions on Iran after its Thanksgiving recess, Senate Majority Leader Harry Reid has said.

If Congress were to override a presidential veto and impose new sanctions, it would violate the terms of the agreement reached in Geneva, which states that the U.S. and world powers may not impose new oil sanctions on Iran for six months. The State Department stopped short today of acknowledging that Congress could break the deal by doing so, but the wording is very clear.

Kerry will continue to lobby Congress, as he did in the run-up to the deal, State Department spokeswoman Jen Psaki said today. The State Department is reaching out to congressional offices to set up meetings, and Kerry spoke to Senate Foreign Relations Chairman Bob Menendez, D-N.Y., by phone this week. He will be in touch with other senators by phone this week, an official told a network pool producer who traveled with Kerry to Geneva.

John Parkinson contributed to this post.