It is beginning to appear now that the machinations of Iranian President Mahmoud Ahmadinejad to win another term in office were so overt, clumsy and brutal as to force a powerful former ally to launch an investigation into his methods.

Supreme Leader Ayatollah Ali Khamenei, whose power rivals that of Ahmadinejad by virtue of his status as both a religious and judicial leader in an Islamic republic, reversed an earlier declaration Monday and ordered an investigation into allegations of voting irregularities in Iran’s presidential election on Friday. Khamenei had earlier dismissed charges of voting fraud and had urged Iranians to accept the re-election of Ahmadinejad, whom the ayatollah had supported strongly in the past.

Ahmadinejad had cracked down ruthlessly as thousands of protesters filled the streets after official election returns showed the president winning re-election with more than 60 percent of the vote. Public support for Ahmadinejad’s primary opponent, Mir Hossein Mousavi, had been so apparent and widespread before the election that suspicions of vote fraud began to mount as soon as the results were announced. Government police responded to street demonstrations with violence over the weekend; one person was reported shot to death and many others wounded in a demonstration on Monday.

The ayatollah’s order for an investigation may put a stop to the violence, but it is hard to tell how an unstable personality like Ahmadinejad’s will interpret the news. In a head-to-head power struggle with Khamenei, Ahmadinejad might lose, and he’s smart enough to know that. But he is also a megalomaniac with delusions of invincibility; he might think he could take on the ayatollah and win.

And the chilling possibility is that he might be right. Khamenei is a revered and powerful figure, but Ahmadinejad has power, too. And guns.

Our common sense tells us that Khamenei has the wherewithal, if he needs it, to follow through with his investigation and call a new election if evidence of irregularities is found. But common sense has a way of being in short supply in Iran.

When we first heard about the charges of vote fraud, we naturally wanted to believe them. That is human nature. Ahmadinejad is an enemy of the United States and of stability in the Middle East in addition to being a dangerously paranoid nutcase, so we would naturally tend to accept allegations that he was a vote thief, as well.

But then we harkened back to 1979, when another paranoid nutcase, a man who held the exalted post that Khamenei now occupies, held his entire country in thrall as he presided over the kidnapping and imprisonment of the Americans who staffed the U.S. embassy in Teheran. The Ayatollah Ruhollah Khomeini, a mad, blind revolutionary who had returned from exile to take over the country after the shah had been deposed, whipped the Iranian people into a frenzy in the days following the initial takeover of the American embassy, and there was little doubt that support for him within Iran was nearly unanimous.

We were initially shocked at the news over the weekend that Ahmadinejad had snatched victory in a race that polls had decreed he would probably lose, but then we thought of that crazy old blind Khomeini, and of the way this blind man led the blind, and we began to think: Well, maybe they did re-elect the crazy guy.

But the brutal crackdown over the weekend was the giveaway. A man who got 60-plus percent of the vote in a presidential election doesn’t need to start shooting protesters. A man who stole the election does.