A reformist challenger to Iranian President Mahmoud Ahmadinejad vowed Tuesday that he would reverse the president's hard-line policies, including the denial of the Holocaust, if he wins the June presidential vote. Mahdi Karroubi, a moderate cleric, is one of four candidates running in the June 12 elections, though he is believed to have less support than the leading reformist challenger to Ahmadinejad, Mir Hossein Mousavi. Karroubi strongly criticized Ahmadinejad for pushing Iran into international isolation and said he has needlessly antagonized the West by claiming the Holocaust was a myth, as well as failed to improve living standards despite huge oil revenues unseen in Iran's history. "The Holocaust is a fact. It is obvious that it has occurred no matter whether the number of people who perished were 6 million or 6,000. (Denying the Holocaust) is of no benefit to Iran," he told a press conference. Iran is also facing an economic crisis, especially with the recent decline in oil prices, and the average citizen has been exposed to soaring food prices over the last year causing increased hardship. The reformist cleric privately told The Associated Press prior to the press conference that it is wrong to assume that Iran's Supreme Leader, Ayatollah Ali Khamenei, is supporting Ahmadinejad for re-election. "During private meetings, he (Khamenei) rejected assertions that he is backing Ahmadinejad for re-election," he said. Karroubi said the biggest challenge for his government, if elected, will be to return Iran to the position and image it had in 2004 when former reformist president Mohammad Khatami, a respected intellectual, stepped down. "Iran has been derailed from the path of development ... expert views, planning and wisdom have been nonexistent during the past four years. The image of the Iranian president has been reduced to the level of a man without wisdom. Changing this image will be the biggest achievement," Gholam Hossein Karbashchi, the campaign manager, said. Ahmadinejad's hard-line policies have provoked international condemnation of Iran and prompted the UN Security Council to impose three rounds of sanctions for its refusal to halt uranium enrichment. The hard-line president provoked global denunciations after he called UN Security Council resolutions "worthless" and "torn bits of paper." Dozens of Western diplomats walked out of a UN conference in Geneva last week and a pair of rainbow-wigged protesters threw clown noses at Ahmadinejad when he called Israel the "most cruel and repressive racist regime." "It was one of his uncalculated statements," Karroubi told reporters. "He calls UN resolutions 'worthless papers' ... and causes troubles for Iran but it is all Iranians who have to pay the price. The president's statements have harmed Iran's interests." While some supporters gave Ahmadinejad a hero's welcome on his return, moderates complained that the president had undermined "the dignity of Iran and Iranians." Karroubi, a former parliamentary speaker, said he will pursue a foreign policy of detente with the West and wouldn't mind meeting President Barack Obama if it would help Iran's national interests.