Iranians choosing new president
Rafsanjani, one of the leading contenders in the poll, casts his ballot on Friday.
Candidates vie for the Iranian presidency.
Former Iranian president Rafsanjani talks to CNN.
Iran's women hope for improved status and more rights.
TEHRAN, Iran (CNN) -- Iranians were casting ballots Friday in a tightly contested presidential election, with opinion polls showing former President Akbar Hashemi Rafsanjani likely headed towards a runoff against either a reformist candidate or a conservative allied with the country's powerful Shiite hierarchy.
Seven candidates are vying to succeed President Mohammed Khatami, a reform-minded cleric barred from seeking a third term.
Though Khatami was elected by landslides in 1997 and 2001, many of his initiatives were blocked by clerical hard-liners who hold vast power under Iran's Islamic system of government.
With high unemployment and a sense of deep social dissatisfaction -- particularly among young people and women -- even conservative candidates talked the language of democracy and reform during the campaign.
Two of the leading contenders, Rafsanjani and Mostafa Moin, have also said they want to improve Iran's strained ties with the West.
Some 48 million Iranians are eligible to vote. If no candidate captures a majority, the two top vote-getters will face each other in a runoff.
Due to high voter turnout, the interior ministry said Friday that voting would be extended by two hours to 9 p.m. (1630 GMT), according to Reuters. Polling stations opened at 9 a.m. (0430 GMT).
The hard-line Guardian Council screened candidates, disqualifying those it deemed unsuitable. More than 1,000 would-be candidates were barred from Friday's election by the council, including all the women who applied.
Rafsanjani, who was president from 1989 to 1997, has been trying to position himself in the political center and has said he is for "a policy of relaxation of tension" with the United States, which has not had formal diplomatic ties with Tehran since the 1979 Islamic Revolution.
"If Americans are sincere in the cooperation, working with Iran, I think the time is right to open a new chapter in our relations with the United States," he told CNN's Christiane Amanpour. (See interview)
"But if the United States wants to continue its obstructions and hostility, then the previous past conditions will persist."
Rafsanjani said the United States has exhibited a "hostile attitude" towards Iran, and "created" the al Qaeda terrorist network, which was behind the September 11, 2001, terrorist attacks.
"If there is terrorism under the name of al Qaeda, the responsibility lies directly with the United States," he said.
On Thursday, the White House released a statement from U.S. President George W. Bush in which he said the electoral process in Iran "ignores the basic requirements of democracy."
"Iran's rulers denied more than a thousand people who put themselves forward as candidates, including popular reformers and women," Bush said.
"The Iranian people deserve a genuinely democratic system in which elections are honest -- and in which their leaders answer to them instead of the other way around."
One of Rafsanjani's main rivals is Moin, a reformist former education minister and protege of Khatami, who has said he will push measures to weaken the control of ruling clerics.
On the other side of the spectrum is the third top contender, Mohammad Baqer Qalibaf, a conservative former police chief widely seen as the favorite of Iran's supreme leader, Ayatollah Ali Khameinei.
Under Iran's system, Khameinei -- not the president -- has the last word in matters of state.
CNN Correspondents Christiane Amanpour and Chandrika Narayan contributed to this report