Mahmoud Ahmadinejad was sworn in to a second presidential term Wednesday with a call for the divided nation to "join hands," but it was greeted by protests in the streets and snubs inside Iran's parliament. The oath-taking ceremony capped a cycle of outrage over claims of massive fraud in the June 12 elections and moved Iran into a new phase: A weakened leadership facing a wider opposition that includes powerful clerics and internal splits among conservatives. The political fissures raise serious questions about Iran's ability to make policy decisions on looming issues such as offers for talks with Washington and efforts to mend ties with European trade partners. "We have now a crisis of authority, where the president and the supreme leader are not able to make big decisions including about the nuclear program and engagement with the US," said Mehdi Khalaji, a senior fellow at The Washington Institute for Near East Policy. US President Barack Obama has given Iran until next month to show willingness to open dialogue after a nearly 30-year diplomatic standoff. Iran's leaders must first try to tone down the worst domestic upheaval since the 1979 Islamic Revolution - which has been fanned by a mass trial that includes prominent reformist political figures. US Secretary of State Hillary Rodham Clinton said Washington still favors direct contact with Iran, but she also lauded those challenging the leadership in Teheran. "Our policy remains the same and we take the reality that the person who was inaugurated today will be considered the president," Clinton told reporters in Nairobi, Kenya. "But we appreciate and we admire the continuing resistance and ongoing efforts by the reformers to make the changes that the Iranian people deserve." In his inaugural address - in tones somewhat quieter than his often-bombastic style - Ahmadinejad called for the nation to put aside its differences and "join hands." But on the streets outside the dark green marble parliament chamber, riot police used batons and pepper spray against hundreds of protesters chanting "Death to the Dictator," witnesses said. Some of the protesters wore black T-shirts in a sign of mourning and others wore green - the color of the opposition movement. A middle-aged woman carried a banner warning Iran's leaders to listen to the people's demands or face the same fate as Shah Mohammad Reza Pahlavi, who was toppled in the Islamic Revolution. Nearly every night, opposition supporters reprise one of the main tactics of the anti-shah movement, shouting "Allahu Akbar," or "God is Great," from rooftops. Inside parliament, the dissent came in the form of boycotts. Key opposition leaders, moderate lawmakers, two former presidents and all three of Ahmadinejad's election challengers stayed away from the swearing-in ceremony. Among the no-shows: former presidents Akbar Hashemi Rafsanjani and Mohammad Khatami and two of the reformist-backed candidates, the top challenger Mir Hossein Mousavi and Mahdi Karroubi. Another powerful snub came from the third candidate, conservative Mohsen Rezaei - a former commander of the Revolutionary Guard who had attended a pre-inauguration ceremony for Ahmadinejad on Monday. His decision to stay away from the main event could reflect growing cracks among conservatives, which could sharply complicate Ahmadinejad's bid to regain political legitimacy. Rezaei has increasingly criticized the leadership for their crackdowns, including calling for high-level probes into abuses after the son of his top aide died in detention. State media reported Tuesday that charges could be filed against police, judges and others for alleged abuses, but it remains unclear whether authorities will follow through. Images on state television showed many empty seats during the swearing-in ceremony, and an opposition lawmakers' Web site said 57 of its 70 lawmakers were not there. Many of the 13 who did attend walked out in protest when Ahmadinejad began to speak, it said. Parliament speaker Ali Larijani maintained 273 of the 290 Iranian lawmakers were present. In his speech, Ahmadinejad demanded that Iran be on an equal footing with other world powers and denounced foreign interference. Iran has accused the US and the West of backing street protests. "We must play a key role in the management of the world," Ahmadinejad said. "We will not remain silent. We will not tolerate disrespect, interference and insults." He added that he would "spare no effort to safeguard the frontiers of Iran" - an apparent reference to Israel and US troops along its borders in Iraq and Afghanistan. But Iran's detention last week of three Americans who strayed across the border while hiking in northern Iraq has added a new point of friction in relations with Washington. Ahmadinejad noted that some Western countries - including the United States, Britain, France, Germany and Italy - did not congratulate him on his election win. "They do not respect the rights of other nations, yet they recognize themselves as the yardstick for democracy," he said, without naming specific countries. "Nobody in Iran is waiting for anyone's congratulations," he added to cheers from lawmakers. A British Foreign Office spokesman said his country has serious concerns over the election, Iran's contentious nuclear program and human rights that must be addressed first. Ahmadinejad did not directly address Obama's outreach for the start of a dialogue on Iran's nuclear program, which the US suspects is geared toward producing weapons. Iran says it only seeks energy-producing reactors. But he said: "Iran is a nation of logic, dialogue and constructive interaction. The basis of our foreign policy is wide and constructive contacts with all nations and independent governments based on justice, respect and friendship." Ahmadinejad mentioned the election crisis only in passing, but issued an apparent warning to demonstrators that authorities would "resist any violation of law and interference." Hundreds of police deployed around parliament Wednesday and two subway stations nearby were closed to the public. Witnesses said at least 10 people were detained by police. Authorities have banned foreign media from covering opposition activities, forcing them to rely on witness accounts and tightly controlled state media. In the days leading up to the inauguration, opposition groups had called protesters into the streets to coincide with the swearing in, spreading the word through postings on reformist Web sites and blogs. The calls showed the protesters resolve to keep confronting the government even though a harsh crackdown by security forces on any street demonstrations has killed at least 30, according to Iran's official toll. Human rights group suspect the death toll is far higher. The opposition - and some powerful conservatives - have also been angered by a mass trial for more than 100 pro-reform figures and protesters accused of challenging the Islamic system. Among those on trial are many prominent reformist activists and political figures, including former Vice President Mohammad Abtahi. The trial had been scheduled to resume Thursday, but was postponed until Saturday after 10 defense lawyers asked for more time to prepare, the state Islamic Republic News Agency reported. Many defense lawyers have complained they have been blocked from access to their clients. The Islamic Iran Participation Front, the biggest pro-reform group, issued a statement saying many of its members remain in detention and denouncing the "kangaroo court" overseeing the mass trial. Aboard Air Force One, White House spokesman Robert Gibbs retreated from an earlier statement that Ahmadinejad is "the elected leader" of Iran. Gibbs said it was "a fact" that Ahmadinejad has been inaugurated, but added it's up to the Iranian people to decide whether the election "was fair."