All eyes on Iran ahead of voting Friday

TEHRAN, June 11 (UPI) -- With hours to go before Iranians head to the polls in a possible upset for the incumbent, demonstrators thronged the streets of Tehran in unprecedented numbers.

Iranians vote for their next president Friday. President Mahmoud Ahmadinejad squares off against former Prime Minister Mir-Hossein Mousavi, former military commander Mohsen Rezaei and former parliamentary speaker Mehdi Karroubi.

The race between Ahmadinejad and his top challenger, Mousavi, has grown particularly tense, as both candidates exchange heated barbs typically unheard of in Iranian politics.

Ahmadinejad is hoping to lure rural voters with a legacy platform operating with the knowledge that no incumbent has been unseated in Iran's 30-year presidential history. Mousavi, meanwhile, enjoys the support of many urban voters, who are frustrated with a poor economic climate and longing for better relations with the West.

Iranian elections officials ordered all campaign activity to stop Thursday morning, 24 hours before the polls open Friday at 8 a.m. local time, Press TV reports.

The Guardian Council, the body charged with overseeing the elections, says it has vetted several allegations of fraud, including buying votes, fake identification cards and other allegations of tampering in the prelude to the Friday vote.

More than 46 million Iranians are eligible to vote in the Friday contest. Regardless of the outcome of the vote, any formal international action will have to wait until the current presidential term expires in August.