Six Iranian presidential candidates participate Friday in a live debate on state TV in Tehran. From left: former vice president Mostafa Hashemitaba; President Hassan Rouhani; Tehran Mayor Mohammad Bagher Ghalibaf; Vice President Eshaq Jahangiri; cleric Ebrahim Raisi; and former culture minister, Mostafa Mirsalim. (Mehdi Dehghan/AFP via Getty Images)

Just a few days ago, hard-line cleric Ebrahim Raisi was the contender to watch in the race to unseat Iranian President Hassan Rouhani. By the weekend, his candidacy was already in doubt.

In the harsh, fast-paced politicking typical of Iran’s campaign season, Raisi's candidacy quickly foundered after his poor performance in a live television debate.

Six candidates approved by Iran’s Guardian Council, a clerical oversight body, took the stage Friday in the first of three planned debates ahead of the May 19 election.

Debates have become a popular feature of the country’s elections, drawing large audiences and producing some of the most memorable moments of recent campaigns. They can also make or break candidates in an election period that takes place over a period of just a few weeks.

Friday’s debate, which was supposed to focus on social issues, saw Rouhani, a moderate, face off against Raisi, a powerful cleric; the hard-line mayor of Tehran, Mohammad Bagher Ghalibaf; a conservative former culture minister, Mostafa Mirsalim; Vice President Eshaq Jahangiri, a moderate and reformist; and former vice president Mostafa Hashemitaba, also a reformist.

Raisi, a potential successor to Ayatollah Ali Khamenei, the nation's supreme leader, and favorite among the conservative camp, kept a very low profile and made little impact, observers said.

He spoke broadly about boosting cash subsidies for the poor, attempting to harness the populist message of former president Mahmoud Ahmadinejad — but with much less charisma.

Raisi “clearly decided to stay calm. … He avoided any major confrontation with other candidates,” said Reza H. Akbari, program manager at the Institute for War and Peace Reporting in Washington, where he researches Iranian politics.

“Regardless of the question, Raisi hammered the key populist policies of alleviating poverty, reducing unemployment and providing government housing,” he said.

But, according to Arash Azizi, a PhD student and writer at IranWire, a portal for Iranian journalists abroad, Raisi “doesn’t seem to have what it takes to perform well in the Islamic Republic’s tricky political arena.

“He didn’t offer a compelling a coherent alternative to Rouhani,” Azizi wrote. Raisi “was the evening’s main loser, and this left open the question of who will now be the main challenger to Rouhani’s candidacy.”

In a country where the supreme leader still dictates foreign and military policy, Iranian presidents are almost guaranteed second terms. But Rouhani, who has been president since 2013, has been criticized for his strategy of diplomacy with the West in exchange for foreign investment — he presided over Iran’s negotiation of a nuclear deal with world powers, agreeing to limit the country’s nuclear program for international sanctions relief — which has failed to improve the lives of ordinary Iranians.

It was clear during the debate whom Rouhani saw as his primary rival — and it wasn’t Raisi, despite the latter’s backing from the religious establishment. Along with his first vice president, Jahangiri, Rouhani went on the offensive against Ghalibaf, the conservative, scandal-prone mayor of Tehran.

Ghalibaf lost to Rouhani in the last election, and he has been accused of corruption during his time as mayor. But Ghalibaf showed himself to be an impressive debater and, also tapping into populist rhetoric, accused the Rouhani administration of “not living among the people.”

“Compared to Raisi, Ghalibaf is a better-known political figure and technocrat with a long history of public service,” Akbari said. “So he has an established support base.”

“Ghalibaf is an articulate and eloquent speaker and very knowledgeable about the nuances of public policy,” he said. “This makes him a strong presidential contender.”

But Jahangiri, acting as Rouhani’s attack dog, confronted Ghalibaf on everything from his past as Iran’s police chief to poor garbage collection in Tehran.

“It’s a slaughter,” tweeted Mohammad Ali Shabani, editor of Iran coverage at Al-Monitor, an online news portal focused on the Middle East. “Jahangiri now attacking Ghalibaf over Tehran trash collection.”

“Mr. Ghalibaf is the mayor of Tehran,” Jahangiri said during the debate, but “he speaks like he is in charge of the whole country.”

Jahangiri’s performance drew praise among Iranians on social media Friday, including a computer-altered photograph showing the vice president as Superman or a gangster smoking a joint and wearing sunglasses. He was widely seen as the winner of the debate.

But according to analysts, Jahangiri is expected to withdraw from the race in favor of his boss. His role was as a “shadow candidate” who could defend Rouhani’s record but also throw blows while allowing the president to remain above the fray.

If he doesn’t drop out, “he will harm Rouhani by splitting the reformist-moderate votes,” Akbari said.

Still, the president’s own debate skills were well received by some Friday night.

One line stood out among Iran watchers in particular, where Rouhani referenced his government’s moves to open Iran up to the world.

“If it wasn’t for this government,” Rouhani said, “even our friends here today couldn’t have campaigned on the Internet.”