VIENNA—Talks aimed to revive Iran’s nuclear pact with global powers were expected on June 2 to adjourn for a week, diplomats said, with the remaining parties to the deal due to meet in the evening to sign off on the move. The adjournment to June 10 would leave only eight days to reach an agreement before Iran’s presidential election, which is likely to usher in a hardline president. Delegates say that while a deal is possible by then, that timeline appears increasingly unlikely. Formal meetings of the remaining parties—Iran, Russia, China, France, Britain, Germany, and the European Union—in a format known as the Joint Commission have punctuated and bookended indirect talks between Iran and the United States on both countries returning to full compliance with the 2015 deal. The EU chairs Joint Commission meetings in the basement of a luxury hotel and leads shuttle diplomacy between Iranian envoys and a …