The landslide re-election of President Mahmoud Ahmadinejad in Iran appears so dubious that even Iran’s supreme leader, a nearsighted cleric, has ordered an investigation.

The votes were counted remarkably quickly. Faced with almost 40 million paper ballots, election officials quickly announced tallies giving the president an insurmountable lead over his moderate opponent. Another fact that caught observers’ attention was the pattern of voting. Ahmadinejad’s 2-1 lead never varied as results came in from the cities and the countryside.

If it were only international observers complaining, it might not be especially significant, but this  is a controversy that has fully engaged the Iranian people. On Monday, hundreds of thousands of demonstrators gathered in Tehran, and throughout the city police have intimidated and beaten protesters.

Although Ahmadinejad is likely to hold on as president, Iran’s highly contested election is proof that anti-U.S. conservatives are not fully in control. We hope the U.S. administration will continue to do what it can to encourage Iran’s moderates.

The U.S. can’t intervene directly in Iran, but it can build international consensus against a potential crackdown on Ahmadinejad’s political opponents. And it can encourage other nations to await the completion of any investigation before recognizing the results of the election.

President Obama said Monday that while the U.S. respects Iranian sovereignty, the voices of the Iranian people should be heard and respected. He noted the eruption of dissent with concern  and spoke out against strong-arm repression by the government.

Among Republicans, including Sen. John McCain, the president’s measured response did not go far enough. “He should speak out that this is a corrupt, flawed sham of an election,” McCain said.

This is political posturing of no consequence. The words of American critics, and even Obama, may be largely irrelevant as Iran copes with internal political forces. The popularity of rival presidential candidate Mir Hossein Mousavi seems to show that the forces of moderation are strengthening.

The country’s supreme leader, Ayatollah Ali Khamenei has announced a limited investigation of the election, while calling for continued support of the Islamic republic.

Meanwhile, public demonstrations continue. It is not clear whether these protests will influence the Iranian government, but U.S. leaders should be alert to any opportunity they provide.

As the president said Monday, the West should be prepared to undertake “tough, hard-headed diplomacy,” to limit the threats from terrorists and nuclear weapons.