Ex-parliament speaker Mehdi Karroubi will if elected president kick-start reforms in Iran but in a "moderate" way that won't trigger the wrath of his hardline opponents, he told AFP in an interview.
Karroubi said he regrets that the "golden opportunity" reformist groups enjoyed under ex-president Mohammad Khatami had been lost but stressed he is against repeating the mistake made then of "radicalizing the reform movement."
"I am going to be moderate. I will adopt the middle path," said the 72-year-old cleric.
Karroubi, who has promised to distribute shares of Iran's state-run oil industry among the populace, said tackling economic woes would top his list of priorities.
Iran - the world's fourth largest crude oil producer - is reeling under an inflation of 25% and an unemployment rate of 13%, which economists say is due to President Mahmoud Ahmadinejad's expansionist policies.
"The first step is to control the deteriorating (economic) situation," said Karroubi, who blamed irregularities in the voting process for his loss to Ahmadinejad in the 2005 presidential race.
Should he win this time, he said he would put together a team of experienced economists to tackle the downturn.
Promising to adopt a "policy of detente" with other countries, the reformist leader said he planned to attract foreign investment and open the Iranian economy, which is 80% state controlled, to the private sector.
Karroubi accused Ahmadinejad, who is seeking a second term as president, of derailing the economy and vowed not to follow the hardline president's style of policy-making.
"These one-man decision makings...the way he distributes money, taking out substantial funds from the foreign exchange reserves and sacking very good economic figures are things which I will not carry forward from Mr. Ahmadinejad," he said.
"If you notice, the cabinet shuffles under Mr. Ahmadinejad have been unprecedented. In less than four years, we have had three new heads of the central bank, at least three interior ministers and two economy ministers."
The ex-speaker, however, is cautious after reformist policies failed during the 1997-2005 era of Khatami.
Several critics and even some of his aides say Khatami wasn't firm enough against hardline establishments in the Islamic republic.
"We were unable to take advantage of the reform movement, otherwise we would not have ended in this situation," said Karroubi.
"The main reason was the ignorance of some reformists. They were either unable to or did not know how to use this opportunity.
"At some point, the reform movement was no longer in the hands of Mr. Khatami or ours...it was a golden opportunity that was lost," he said.
Karroubi said Iran's controversial uranium enrichment program, which the West fears is masking an atomic weapons drive, "will not be stopped."
The nuclear issue, he added, "is not within my domain... it is in the (supreme) leader's" domain.
"The reality is that the United States has done bad to us and those who have done bad to others, they should take good initiatives to make it up," he said commenting on the diplomatic efforts taken by U.S. President Barack Obama towards Iran.