MARGARET BRENNAN posted:

LAUSANNE, Switzerland -- A group of world powers have agreed on some technical specifics and a broad political agreement with Iran that will limit but not destroy its nuclear program.

"Today we have taken a decisive step. We have reached solutions on key parameters of a joint comprehensive plan of action," European Union foreign policy chief Federica Mogherini said Thursday. "The political determination, the good will and the hard work of all partners made it possible and let us thank all delegations for their tireless dedication. This is a crucial decision laying the agreed basis for the final text of the joint comprehensive plan of action."

Mogherini said said the parties will now work on drafting the text of the comprehensive plan, with a goal completing the work by June 30. The working title is the Joint Comprehensive Plan of Action or the JCPOA.

A diplomatic source told CBS News that this agreement tackles about 20 percent of the issue and defers decision making on many of the larger implementation concerns until the end of June. That is when the existing interim agreement that has kept Iran's nuclear program frozen during negotiations will expire.

CBS News is told that the agreement does include technical elements that will be disclosed in some form in order to allow the U.S. to demonstrate to Congress it can theoretically guarantee a one year breakout time before Iran would be able to build a bomb. That one year breakout time is the benchmark for success that the White House has set for itself.

Tehran denies that it has any intention of building an atomic weapon but it is negotiating because it wants sanctions lifted. Iranian negotiators want to be able to disclose what they have gained but are hesitant to release information on the concessions made thus far.

During the course of talks this week CBS News reported that the deal being offered would set limits on Iran's nuclear program for the next 15 years with the most stringent restrictions hitting during the first decade. Both Senior US and European officials emphasized that there was disagreement with Iran over what would happen during the final five years of that accord.

Specifically at issue was how much nuclear enrichment it would be allowed to carry out and how quickly it could carry out that research and development. The offer included plans to lift financial, economic and oil sanctions on Iran that had been levied by the U.S. and European Union. However, there had been disagreement over how to structure the lifting of the U.N. Security Council sanctions that have cut Iran off from the global markets and made it an international pariah. There were also disputes over how to make Iran's existing atomic stockpile unusable in a warhead.

It is not yet clear whether or how many of these issues have been resolved.

Within hours, a statement is expected to be made by representatives of the European Union and Iran at the Ecole Polytechnique Federale de Lausanne.

Israel and Saudi Arabia have already expressed that they aren't ok with this deal. What does the future hold?