For years Iran has derided the United States as the "Great Satan," while Obama's predecessor George W. Bush labelled Tehran part of an "axis of evil" and refused to rule out military action over Iran's nuclear programme.

But now Tehran has an opportunity to mend three decades of broken relations with Washington and pursue a negotiated solution to the nuclear standoff with the West which has seen the UN Security Council impose three sets of sanctions.

The next president will not take the big decisions -- the Iranian political system gives the final say on strategic issues to supreme leader Ayatollah Ali Khamenei.

But whoever wins this month's election will play the key role in implementing the policy and handling what may be a turning point in Iran's relations with the outside world.

"The core of Iran's foreign policy after the election will revolve around how to respond to Obama's moves and managing the nuclear talks with global powers," political analyst Mashaallah Shamsolvaezin told AFP.

"Until now, it was easy for Iran to blast the United States, especially after what Bush did," Shamsolvaezin said.

"But under Obama things have changed. There is a belief among Iranian leaders that, if required, Obama has the ability to turn the world against Iran, which is why Iranian leaders have to resolve all the outstanding issues with Washington during Obama's term."

Soon after taking office in January, Obama said his administration was ready to extend a diplomatic hand to Iran if it "unclenches its fist."

And on Thursday, Obama made a significant gesture to Iran, becoming the first sitting US president to acknowledge US involvement in the 1953 coup which overthrew the government of Prime Minister Mohammad Mossadegh, a longstanding Iranian demand.

But US officials have also made clear that if Tehran spurns the overtures, Washington will seek much tougher UN action over Iran's nuclear programme, which Western governments suspect is cover for a drive for an atomic bomb.

Iran has made some conciliatory gestures of its own, taking part in a US-backed conference on Afghanistan in The Hague on March 31 and offering its help in stabilising its eastern neighbour where US-led troops are battling a raging insurgency.

Shamsolvaezin said Tehran knows Washington needs its help in maintaining regional stability. "It will play this card in its foreign policy," he said.

Frederic Tellier, senior Iran analyst with Brussels-based think-tank the International Crisis Group, said: "What Iran seeks is a better managed, regulated and respectful rivalry."

For Iran, any possible dialogue with the United States will have to be "wide-ranging," Tellier wrote in his latest report.

Incumbent hardliner Mahmoud Ahmadinejad repeatedly antagonised Western governments by aggressively championing Iran's nuclear programme and rejecting the slightest concession to allay their suspicions.

Defying repeated UN Security Council ultimatums to freeze uranium enrichment, Ahmadinejad said Iran's drive to master the nuclear fuel cycle was a "train without brakes and no reverse gear."

His leading challenger in Friday's election, moderate former premier Mir Hossein Mousavi, has promised to work to improve Iran's relations with the outside world but analysts said they doubted there would be much change in nuclear policy if he were elected.

"I don't think the Islamic republic will compromise on the nuclear issue whoever becomes president, be it Ahmadinejad or Mousavi," said Sayed Mohammad Marandi, head of North American studies at Tehran University.

"It has nothing to do with who becomes president. If Iran feels that Obama has recognised its enrichment programme, Iran will give them the guarantees they are seeking."

But Marandi warned a tit-for-tat approach from Iran could not be ruled out, if Washington again steps up pressure with "the aim of hurting Iran."

"They (Iranian officials) will not sit and watch. If they (US officials) decide to play hard ball, so will Iran."

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