Iranian President Mahmoud Ahmadinejad, right, receives a certificate declaring him as president of the Islamic Republic of Iran from Supreme Leader Ayatollah Ali Khamenei in Tehran on Monday. (Reuters)

Iran's supreme leader bestowed his formal endorsement on Mahmoud Ahmadinejad's second term as president on Monday but withheld a powerful symbolic gesture — the kisses and close embrace that portrayed their bond four years ago.

The awkward and halting moment came when Ahmadinejad leaned forward to kiss Ayatollah Ali Khamenei. But the supreme leader raised his left hand and momentarily stopped Ahmadinejad, who spoke a few words and then kissed Khamenei's robe.

The uneasy body language reflected much of the political tension and collateral damage since the disputed June 12 election sent Iran into its worst internal unrest since the 1979 Islamic Revolution.

Ahmadinejad begins his next four-year term as a hugely polarizing figure: backed by the Islamic system but scorned by millions of opponents who claim the vote was rigged.

Khamenei, meanwhile, has been rattled for the first time by protesters questioning the near limitless power of the theocracy he controls.

Both now are battered and bound together against the pro-reform backlash. But it's still a potentially testy relationship.

Khamenei appeared to signal he is willing to stand by Ahmadinejad, as he has since the election, but that the supercharged political climate requires new sensitivities to public opinion.

Ahmadinejad also crossed a political line last month by resisting Khamenei's calls to dismiss a top aide, whom Ahmadinejad eventually dumped.

After Ahmadinejad's surprise election in 2005, Khamenei allowed him to kiss his hand in a show of profound loyalty. Then, Khamenei drew him close and kissed him on both cheeks with a benevolent smile. This time, Ahmadinejad moved toward Khamenei but was offered only the chance to kiss the leader's robe, a gesture of respect but far more restrained than four years ago.

"It's as if Khamenei was saying, 'Hey, listen. Don't think that we are this close team we once were,'" said Patrick Clawson, deputy director at the Washington Institute for Near East Policy.

The state Islamic Republic News Agency reported that Ahmadinejad had a cold, suggesting this could be the cause for the more cautious reception.

Notables missing from ceremony

Even the ceremony itself displayed Iran's seemingly unbridgeable rifts.

The list of no-shows was a roster of top critics of the election outcome and the fierce crackdowns. The absent included runner-up Mir Hossein Mousavi and another pro-reform candidate, Mahdi Karroubi, and two former presidents: Akbar Hashemi Rafsanjani and Mohammad Khatami.

Also missing were any members from the family of the patriarch of the Islamic Revolution, the late Ayatollah Ruhollah Khomeini, whose portrait looked over the hall in central Tehran.

Khomeini's relatives do not have high-profile political duties, but some have been critical of hard-liners in recent years.

Iran's main state TV channels did not have live coverage of the ceremony in an apparent effort by the Islamic rulers to avoid emphasizing the boycotts to domestic audiences. But Iran's state-funded channels in Arabic and English broadcast extensive images of Khamenei and Ahmadinejad — possibly seeking to display a sense of high-level solidarity on the international stage.

Ahmadinejad's next stop is to take the oath of office Wednesday in parliament, where many pro-reform lawmakers have echoed the claims of fraud in the election. Opposition groups could also use the occasion to rally another wave of marches and protests.

Sporadic clashes broke out late Monday in north Tehran after security forces boosted patrols, witnesses said. Later in the night, many of Ahmadinejad's opponents went on their rooftops and chanted, "Death to the dictator."

In remarks quoted on state TV, Khamenei gave no hint of any change in attitudes toward Ahmadinejad. He called the president "brave and hardworking" and described the election as a "golden page" in Iran's political history. Last week, Ahmadinejad sought to deflect claims of discord with the ruling establishment by saying his rapport with Khamenei is "like father and son."