Last Updated 6:35 p.m. ET
As thousands of protesters gathered in Tehran Tuesday for the second straight day of large demonstrations against Iran's presidential elections, Supreme Leader Ayatollah Ali Khamenei called for national unity.
Khamenei called for Iranians to unite behind the cleric-led ruling system despite rival demonstrations and street clashes between supporters of President Mahmoud Ahmadinejad and his reformist opponent Mir Hossein Mousavi, who says Ahmadinejad stole re-election.
There's a lot of political maneuvering going on to contain the unrest, and one sign of that is the arrest of at least 100 prominent opposition members - including some senior members of the clergy, reports CBS News correspondent Elizabeth Palmer from Tehran.
Khamenei also said representatives of all four candidates should be present for any limited recount of disputed ballots, which the country's cleric-led Guardian Council said Tuesday that .
"In the elections, voters had different tendencies, but they equally believe in the ruling system and support the Islamic Republic," said Khamenei, who is Iran's ultimate authority.
The powerful Guardian Council agreed to a partial recount of the ballots in what they called contested areas. They also said they'd look into reports of people using false IDs to vote, Palmer reports.
But Mehdi Karoubi - another opposition candidate who came third on the ballot - said that's not good enough.
"A really thorough investigation would conclude that the vote is invalid. Otherwise this government will be illegitimate," he told Palmer.
A spokesman for the Guardian Council, Abbas Ali Kadkhodaei, was quoted on state TV as saying the recount would be limited to voting sites where candidates claim irregularities took place. He did not rule out the possibility of canceling the results, saying that is within the council's powers, although nullifying an election would be an unprecedented step.
But some observers are still skeptical of the Council's intentions.
"It's a little difficult to imagine that they're going to do a good job, because the Council of Guardians is the organization that basically disqualifies anybody they don't like from the election," Gary Sick, a former White House advisor on Iran told CBS News. "They have a history of taking a partisan position, so it's difficult to see them doing a serious investigation."
Sick pointed out, however, that given the furor generated by these election results and the fierce opposition from within the country, "It may be harder to run a cover-up than it had appeared on the surface."
More likely, the dramatic intervention by Khamenei and the Guardian Council could buy time in hopes of reducing the anti-Ahmadinejad anger. The prospect of spiraling protests and clashes is the ultimate nightmare for the Islamic establishment.
Today, it was the turn of President Ahmadinejad's supporters to fill Tehran's Freedom Square - exactly where thousands of opposition supporters gathered yesterday. These vast rallies and counter-rallies are the public face of the huge power struggle taking place behind the scenes, Palmer reports.
Today's opposition rally was cancelled after the defeated candidate Mir Hossein Mousavi warned his supporters to stay off the streets for their own protection. But guided by Twitter, young people streamed to an informal meeting place anyway, Palmer reports.
"This repressive regime cannot continue like this," one young Mousavi supporter told Palmer by phone.
A witness tells The Associated Press that the pro-Mousavi rally stretched more than a mile along Vali Asr avenue, from Vanak Square to the headquarters of Iranian state TV.
Security forces did not interfere, the witness said, and the protest lasted from about 5 p.m. to 8 p.m. Other witnesses told the AP that about 100 people were still protesting in front of state TV around 9:45 p.m.
A correspondent for state-controlled Press TV correspondent said the crowd carried banners of Mousavi, wore green headbands and covered their mouths in an apparent defense against tear gas.
The government barred foreign media from covering rallies in Tehran - even the state-organized demonstration, where government officials urged the crowd not to let the election divide the nation and said the unrest would not threaten Iran's Islamic system. That rally drew thousands of people waving flags and pictures of Iran's supreme leader in an apparent attempt to reclaim the streets for the government.
The Press TV correspondent at the pro-reform rally told the anchor by telephone that a crowd she called "huge" and "massive" was carrying banners of Mousavi, wearing green headbands and covering their mouths in an apparent defense against tear gas. She said the crowd was marching farther north, toward Tajrish Square.
The clerical government appears to be trying to defuse popular anger and quash unrest by announcing the limited recount even as it cracks down on foreign media and shows its strength by calling supporters to the streets.
"This nation will protect and defend its revolution in any way," Gholam Ali Haddad Adel, a prominent lawmaker and supporter of President Mahmoud Ahmadinejad, said as the crowd in Vali Asr Square pumped their fists in the air and cheered in support, images on state-run television showed.
Iranian state media said the government organized the rally to demand punishment for those who protested violently after a larger demonstration Monday by hundreds of thousands of Mousavi supporters. Mousavi has said he won Friday's balloting and has demanded the government annul Ahmadinejad's victory and conduct a new election.
Iran's state radio said in clashes from Monday's protest - the first official confirmation of deaths linked to the street battles following the disputed election.
Witnesses saw people firing from the roof of a building used by a state-backed militia after some Mousavi supporters set fire to the building and tried to storm it.
Mousavi supporters had called for demonstrations Tuesday but Mousavi said in a message in his Web site he would not be attending any rally and asked his supporters to "not fall in the trap of street riots" and " ."
Ahmadinejad Tuesday after delaying a trip for a day but did not mention the Iranian election or unrest. Instead, he focused on the traditional target of the Islamic Republic's ire, the United States.
"America is enveloped in economic and political crises, and there is no hope for their resolution," he said through an interpreter. "Allies of the United States are not capable of easing these crises."
In Washington, U.S. President Barack Obama said that he believes the ayatollah's decision to order an investigation "indicates he understands the Iranian people have deep concerns."
He also expressed hope that the Iran's internal political friction could bring about change in the country.
"I do believe that something has happened in Iran," with Iranians more willing to question the government's "antagonistic postures" toward the world, Mr. Obama said.
But at the same time, Mr. Obama said it would not be helpful if the United States was seen by the world as "meddling" in the issue.
Foreign reporters in Iran to cover last week's elections began leaving the country Tuesday after Iranian officials said they would not extend their visas.
Authorities restricted other journalists, including Iranians working for foreign media from reporting on the streets, and said they could only work from their offices, conducting telephone interviews and monitoring official sources such as state TV.
At least 10 Iranian journalists have been arrested since the election, "and we are very worried about them, we don't know where they have been detained," Jean-Francois Julliard, secretary general of Reporters Without Borders told AP Television News in Paris. He added that some people who took pictures with cell phones also were arrested.
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