TEHRAN, March 14 - Just weeks ago, the Iranian government's combative approach toward building a nuclear program produced rare public displays of unity here. Now, while the top leaders remain resolute in their course, cracks are opening both inside and outside the circles of power over the issue.
Some people in powerful positions have begun to insist that the confrontational tactics of President Mahmoud Ahmadinejad have been backfiring, making it harder instead of easier for Iran to develop a nuclear program.
This week, the United Nations Security Council is meeting to take up the Iranian nuclear program. That referral and, perhaps more important, Iran's inability so far to win Russia's unequivocal support for its plans have empowered critics of Mr. Ahmadinejad, according to political analysts with close ties to the government.
One senior Iranian official, who asked to remain anonymous because of the delicate nature of the issue, said: "I tell you, if what they were doing was working, we would say, 'Good.' " But, he added: "For 27 years after the revolution, America wanted to get Iran to the Security Council and America failed. In less than six months, Ahmadinejad did that."
One month ago, the same official had said with a laugh that those who thought the hard-line approach was a bad choice were staying silent because it appeared to be succeeding.
As usual in Iran, there are mixed signals, and the government does not always speak with the same voice.
On Tuesday, both Mr. Ahmadinejad and the nation's supreme leader, Ayatollah Ali Khamenei, insisted in public speeches that their country would never back down. At the same time, Iranian negotiators arrived in Moscow to resume talks - at Iran's request - just days after Iran had rejected a Russian proposal to resolve the standoff.
Average Iranians do not seem uniformly confident at the prospect of being hit with United Nations sanctions.
From the streets of Tehran to the ski slopes outside the city, some people have begun to joke about the catch phrase of the government - flippantly saying, "Nuclear energy is our irrefutable right."
Reformers, whose political clout as a movement vanished after the last election, have also begun to speak out. And people with close ties to the government said high-ranking clerics had begun to give criticism of Iran's position to Ayatollah Khamenei, which the political elite sees as a seismic jolt.
"There has been no sign that they will back down," said Ahmad Zeidabady, a political analyst and journalist. "At least Mr. Khamenei has said nothing that we can interpret that there will be change in the policies."
But, he said, "There is more criticism as it is becoming more clear that this policy is not working, especially by those who were in the previous negotiating team."
There are also signs that negotiators are starting to back away, however slightly, from a bare-knuckle strategy and that those who had initially opposed the president's style - but remained silent - are beginning to feel vindicated and are starting to speak up.
A former president, Mohammad Khatami, recently publicly criticized the aggressive approach and called a return to his government's strategy of confidence-building with the west.
"The previous team now feels they were vindicated," said Nasser Hadian, a political science professor at Tehran University who is close to many members of the government. "The new team feels they have to justify their actions."
Ayatollah Khamenei, who has the final say, issued a strong defense of Iran's position on Tuesday.
"The Islamic Republic of Iran considers retreat over the nuclear issue, which is the demand of the Iranian people, as breaking the country's independence that will impose huge costs on the Iranian nation," he said.
"Peaceful use of nuclear technology is a must and is necessary for scientific growth in all fields," Ayatollah Khamenei said. "Any kind of retreat will bring a series of pressures and retreats. So, this is an irreversible path and our foreign diplomacy should defend this right courageously."
In a speech in northern Iran, Mr. Ahmadinejad called on the people to "be angry" at the pressure being put on Iran.
"Listen well," the president said to a crowd chanting "die" as they punched the air with their fists. "A nuclear program is our irrefutable right."
When Mr. Ahmadinejad took office, he embraced a decision already made by the top leadership to move toward confrontation with the West about the nuclear program. From the sidelines, Mr. Ahmadinejad's opponents remained largely silent as his political capital grew.
Iran's ability to begin uranium enrichment, and to remove the seals in January at least three nuclear facilities without any immediate consequences, was initially seen as a validation of the get-tough approach.
But one political scientist who speaks regularly with members of the Foreign Ministry said that Iran had hinged much of its strategy on winning Russia's support. The political scientist asked not to be identified so as not to compromise his relationship with people in the government.
The political scientist said some negotiators believed that by being hostile to the West they would be able to entice Moscow into making Tehran its stronghold in the Middle East. "They thought the turn east was the way forward," the person said. "That was a belief and a vision."
The person added, "They thought, 99 percent, Russia would seize the opportunity and back the Iranian leaders."
The route forward remains unclear as Iran tries to regain a sense of momentum.
There is a consensus here that Iran has many cards to play - from its influence with the Shiites in Iraq to its closer ties to Hezbollah in Lebanon, to the prospect of using oil as a weapon. But the uncertainty of appearing before the Security Council, and the prospect of sanctions, has led some here to begin to rethink the wisdom of fighting the West head-on, analysts said.
Professor Hadian said he believed that for Iran to fundamentally change course the situation for Iran would have to first grow much worse.
"There are concerns to keep the situation calm," said Mr. Zeidabady, the journalist. "We have received orders not even to have headlines saying the case has been sent to the Security Council. Although the situation is very critical, they want to pretend that everything is normal. They do not want to show the country is coming under pressure and lose their supporters."
Nazila Fathi contributed reporting for this article.