But there is a big caveat: Half of the respondents in the IPPO poll either said they were undecided or declined to disclose their choice.

There are other warning signs for Rouhani. Out of the top three candidates, Raisi generated the most positive mentions on social media, while Rouhani drummed up the most negative sentiment, according to an analysis of about 60,000 Persian-language social media, blog and message board posts conducted by data measuring firm Babel Street between April 9 and May 10.

The results “point to Iranian’s discontent with the status quo under Rouhani, even as election polls place him in the lead,” Babel Street said in a report.

Social media analysis by the Eurasia Group shows Rouhani leading on momentum, but Raisi surging to a dead heat with the president on their ability to identify with voters’ concerns. Taking into consideration a broader array of issues, social sentiment lends support to a Raisi upset.

Qalibaf’s exit gives Rouhani a clearer path to victory by lowering the odds he’ll face a runoff election, according to Eurasia Group. The perception that Raisi is a potential successor to Supreme Leader Ayatollah Ali Khamenei may also stir moderate and reformist voters to action, the risk consultancy concluded.

But Eurasia Group nevertheless lowered the probability of Rouhani’s re-election to 60 percent based on growing efforts by conservative elites and security forces loyal to Khamenei to mobilize support for Raisi, along with a lack of reliable polling data and history of surprises in Iranian elections.