In their third and final televised debate Friday, Iran’s eight presidential candidates traded pointed accusations, including blaming one of their number for his role in responding to anti-government protests and criticizing another for the lack of progress in talks on the country’s nuclear program.

Political differences quickly turned personal, with several candidates bringing up episodes from their rivals’ careers that many might have preferred to keep in the shadows, offering a rare glimpse into the often bitter disputes that roil the top echelons of the Islamic republic’s political system.

But after two lackluster debates that viewers and participants alike criticized for their lack of substance and competitiveness, Friday’s clashes may provide some of the spark that Iranian authorities have been seeking to energize what has been a low-energy campaign, generating little public interest.

Former foreign minister Ali Akbar Velayati, a Johns Hopkins-trained pediatrician, slammed the job performance of Iran’s current lead nuclear negotiator, Saeed Jalili.

“You were in charge of the nuclear case for several years, and we haven’t taken a single step forward,” Velayati said, denouncing Jalili’s avowed “resistance” policy. “Diplomacy isn’t about toughness or stubbornness.”

Who will be the next president of Iran? Here are the eight candidates running in the upcoming presidential election.

Both men are considered part of the conservative wing of Iranian politics and close to the country’s supreme leader, Ayatollah Ali Khamenei.

In one of the first instances of a reformist politician publicly voicing frustration about the repressive aftermath of Mahmoud Ahmadinejad’s 2009 reelection, former vice president Mohammad Reza Aref said, “I don’t want to open the case of 2009, but I silenced myself for four years, and I was in pain.”

Aref complained that several of his supporters had been arrested at a recent campaign event but urged Iranians to vote anyway on June 14, saying in his closing statement, “Not voting is not the way to express your protest.”

The debate’s most heated exchange took place between Tehran’s mayor, Mohammad Bagher Ghalibaf, and former lead nuclear negotiator Hassan Rouhani, the only cleric in the race.

After Rouhani said that, if he is elected, his government would “provide security and tranquility to all Iranians.” Ghalibaf challenged him, accusing Rouhani of selectivity about who should benefit from such protection. He was referring to Rouhani’s failure to give protesters permission to rally in 2003, when he was head of the Supreme National Security Council. The protests took place anyway and spiraled out of control, leading to three weeks of unrest.

Ghalibaf headed Iran’s police forces at the time, and a recently released recording from which he has been trying to distance himself has him taking credit for suppressing the 2003 protests.

Visibly surprised by Ghalibaf’s admonition, Rouhani responded: “I have so much information in my memory, but I’m not willing to destroy my opponents, nor am I willing to expose top-secret documents. I’m not arguing about what police did at that time. I am arguing against Mr. Ghalibaf’s debate tactics.”