Iran's supreme leader Ayatollah Khamenei urged the public not to vote for pro-Western candidates in the June 12 presidential election, though he gave no clear indication of whether he is supporting hard-line President Mahmoud Ahmadinejad.

The critical election pits Ahmadinejad against reformist challengers at a time when the United States — under the Obama administration — is pursuing dialogue with its longtime adversary after years of shunning Iran.

The reformists seek an easing of social and political restrictions at home and better ties with the West. They see a strong opportunity to unseat Ahmadinejad, who has become increasingly unpopular because of Iran's economic woes. Critics also say he has needlessly enflamed world anger with his statements casting doubt on the Holocaust and calling U.N. resolutions "worthless papers."

Challenging his re-election bid are a conservative former Revolutionary Guards commander and two reformist candidates who have attacked him over his handling of the economy and for pursuing a hard-line foreign policy that they say has plunged Iran deeper into international isolation.

"Do not allow those who would throw their hands up and surrender to enemies and defame the Iranian nation's prestige to get into office," Khamenei said in a televised speech in Bijar, in western Iran.

"(Don't vote for) those who would provoke the greed of the enemies of the Iranian nation and be used by them to create divisions within the nation and take people away from their religion, principles and their revolutionary values."

It was not clear whether he was targeting a specific candidate, though Khamenei has in the past denounced reformists, saying they speak the language of the West. In 2000, Khamenei called reformist newspapers "bases of the enemy." Within days, more than a dozen reformist papers were closed down.

Hard-liners have also denounced the reformist government of former President Mohammad Khatami, in office from 1997 to 2005, saying he caved in to Western pressure over Iran's nuclear activity and suspended uranium enrichment. They hail Ahmadinejad, saying he defied the West and resumed uranium enrichment, a process that can be used to make fuel for both nuclear energy or nuclear weapons.

Obama has been seeking to engage Iran in direct dialogue and restart international negotiations over its nuclear program, which years of sanctions and isolation have failed to stop. The U.S. and its European allies fear Iran's nuclear activity is aimed at developing weapons under the cover of a civilian energy program, though Iran denies that.

Khamenei holds ultimate power in Iran, at the top of the clerical hierarchy above elected figures. His support is crucial for any candidate to win the vote, though he has never made his choice public.

While he has offered glowing praise of Ahmadinejad in the past, he has at times rebuked him publicly. Last August, Khamenei offered glowing praise of Ahmadinejad for "standing up" to the West on the nuclear issue and urged him to run his government as if he would eventually serve a second term.

But earlier this month, Khamenei publicly rebuked the president for his removal of a top official, a rare show of discontent with Ahmadinejad.

Last week, Khamenei said people should vote for candidates who "understand the pain of the people ... be intimate with the people, live in a simple and modest way and get away from corruption and aristocracy."

Ahmadinejad supporters hailed those comments as proof that Khamenei supports Ahmadinejad, a populist who grew up in a poor family and presents himself as a man of the people who prefers a simple way of life and dress.

Hamid Reza Taraqi, leader of a hard-line political party called the Islamic Coalition Society that is supporting Ahmadinejad in the election, said the supreme leader's latest remarks were aimed at the two reformist candidates.

"It was reformists who used to give in to Western pressure and surrender to the West under former reformist President Khatami. It was also reformists who were supported by the West," Taraqi said.

One of the reformist candidates, former parliament speaker Mahdi Karroubi, has promised to reverse Ahmadinejad's policies and has said he wouldn't mind meeting President Barack Obama if it would help Iran's national interest.

The other reformist challenger, former Prime Minister Mir Hossein Mousavi, has billed himself as capable of straddling Islamic values and the freedom necessary to liberalize Iran's economy and politics.