Anti-war activists rally outside the White House in Washington in support of the Iran nuclear deal August 30.

The Obama administration began carrying out the Iran nuclear deal on Thursday as time expired on Republican efforts to derail it, appointing a senior diplomat to ensure that Tehran moves further away from bomb-making capability and outlining a months-long process before Western nations will start easing economic sanctions.

Senators failed to reach the threshold for a measure to keep all sanctions in place on Iran until it recognizes Israel and releases all imprisoned Americans, and then on a resolution expressing disapproval of the nuclear agreement. Two previous votes in recent days against the Iran deal also failed, and a 60-day window in the Republican-controlled Congress to prevent President Barack Obama from implementing the seven-nation pact was set to close Thursday night.

Shortly after the votes, the State Department named Stephen Mull as “lead coordinator for Iran nuclear implementation.” Mull, who has served as ambassador to Poland and in other top diplomatic posts, takes on the “crucial” responsibility of shepherding an agreement “which will make the United States, our friends and allies in the Middle East, and the entire world safer,” Secretary of State John Kerry said.

The accord clinched by the U.S., Britain, China, France, Germany, Russia and Iran on July 14 will provide Iran hundreds of billions of dollars in relief from international sanctions in exchange for a decade of constraints on the country’s nuclear program. While the Republican-led Congress’ objections posed the last serious threat to the package, the sides will need months to put the deal into place.

Washington expects Tehran to begin on Oct. 18 making major changes to its main site for enriching uranium at Nantanz, its underground nuclear facility at Fordo and its heavy water reactor at Arak. Uranium can be enriched as part of fuel production or for nuclear weapons development.

At Nantanz, Iran will have to uninstall thousands of centrifuges and place them in storage controlled by the U.N’s International Atomic Energy Agency. It must also remove electrical infrastructure and pipework. The entire process could take months, senior U.S. officials said. They weren’t authorized to speak publicly on the process and demanded anonymity.

No sanctions relief will occur until all the steps are completed, they insisted, but they said Obama would start issuing waivers on Oct. 18 so that the U.S. can fulfill its end of the bargain once the IAEA verifies Iran’s full compliance. The European Union will undertake a similar process for actions it plans to take, such as ending a ban on imports of Iranian oil.

Obama also will instruct U.S. agencies such as the State Department and Treasury Department to lay the groundwork for relieving sanctions on Iran.

Iranian compliance also will end U.N. penalties, though some will remain. These include an arms embargo that lasts up to 5 years, a ballistic missile technology ban for up to 8 years, and a ban on transferring any unauthorized nuclear goods, which stays in place for a decade.