Expert-level talks between Iran and the P5+1 regarding an interim nuclear deal have been extended through Saturday, adding another day of negotiations.

The current round of negotiations began on Thursday in Geneva, after an Iranian delegation abruptly abandoned talks last week in protest over US enforcement of existing sanctions.

The interim deal — curbing but not freezing Iran’s nuclear program in return for an easing of non-core sanctions — was reached in Geneva last month, but has not been implemented because “technical details” have not been finalized.

The Obama administration announced Thursday that it would veto a newly proposed Senate bill that would increase sanctions against Iran should the country fail to comply with the terms of any nuclear deal.

Iranian Foreign Minister Mohammad Javad Zarif has indicated that such legislation, if passed, would torpedo the ongoing talk.