Iran's incumbent president — the man behind the historic nuclear deal — appears poised to win a second term on Friday, but analysts are not discounting a surprise victory by the conservative candidate believed to have the supreme leader's backing.
A vote to reinstall President Hassan Rouhani is seen as an endorsement for building ties with the international community, while an upset result would portend a more inward-looking Iran and put a hard-line administration on a collision course with President Donald Trump.
"The fate of the 2015 nuclear deal potentially hangs in the balance depending on the outcome of the election," Helima Croft, global head of commodities strategy at RBC Capital Markets, said in a research note.
The accord between Iran and six world powers, including the United States, lifted crippling economic sanctions on the country in exchange for limitations on its nuclear program. Since it took effect, Iran has hiked oil output by about a million barrels a day and lined up European and Asian oil majors eager to invest in its energy industry.