The two leaders of Iran’s not-so-loyal opposition will appear together tomorrow at Tehran University, when Mir Hossein Mousavi, the challenger to President Ahmadinejad, makes a public appearance alongside Ayatollah Ali Akbad Hashemi Rafsanjani, the former president and billionaire who supported Mousavi’s campaign. Rafsanjani, who’s boycotted his turn at leading Friday prayers since June 12, will deliver a closely watched sermon that is expected to lay out a direct challenge to Ahmadinejad. The fact that Mousavi will attend the event means that it’s likely that other leading reformists will be there, including former President Khatami and cleric Mehdi Karroubi, a former speaker of Iran’s parliament who also ran against Ahmadinejad in the June 12 election.

It’s likely that the event will attract a huge crowd, perhaps tens or hundreds of thousands.

Iran’s intelligence minister, a close ally of President Ahmadinejad and a follower of Ayatollah Mesbah Yazdi, has already warned the opposition about tomorrow’s event. “The vigilant Iranian nation must be aware that tomorrow’s sermon should not turn to an arena for undesirable scenes,” said Intelligence Minister Gholamhossein Mohseni-Ejei. “Hopefully we will not have a security question in Tehran in the coming days.”

Neither Rafsanjani nor Mousavi, who isn’t expected to speak, will call for a revolt. But they haven’t abandoned their opposition. Rafsanjani, who hasn’t spoken directly about the election results since June 12, has reportedly been mustering clerical and establishment opposition — including the business community — behind the scenes, and a political party that he leads has called the reelection of Ahmadinejad illegitimate. Mousavi continues to reject the election results, and he’s announced plans to create a nationwide political party. Through his web site and in a limited number of public appearances since the crackdown, Mousavi has spoken out forcefully against the rigging of the vote, presented a detailed challenge to the result, and visited with relatives of those killed or arrested.

From AP:

The pro-Mousavi Web site mowjcamp.com said reformist leaders will hold street protests after attending the Friday prayers.

Thursday night, several hundred supporters gathered, some chanting “death to the dictator,” as Mousavi and his wife visited the family of Sohrab Aarabi, 19, who disappeared during a June 15 protest, according to mowjcamp.com. Footage from the visit posted on the Web showed Mousavi moving through a crowd of well-wishers inside Aarabi’s family home to his parents to express condolences.

Aarabi disappeared during a June 15 protest, and his family searched for weeks for news of his fate. They were finally notified on Saturday that he had been shot in the chest and died during the crackdown on postelection protests. Aarabi was buried Monday in the vast Behesht-e-Zahra cemetery on the outskirts of Tehran.

The report added:

“We won’t let the blood of these youth go in vain,” Mousavi told Aarabi’s family during the visit, according to the Web site norooznews.org.

Aarabi’s mother, Parvin Fahimi, said she would take the case of her slain son to domestic and, if necessary, international courts, the site reported.

Hundreds of candles were lit in the streets of the Tehran neighborhood where the family lives, mowjcamp reported. Inside the home, the walls were hung with pictures of Aarabi wearing a green scarf over his shoulders — the color of Mousavi’s opposition movement.