WASHINGTON - The confused aftermath of Iran's presidential election is complicating the Obama administration's planned outreach to the Islamic republic and underscoring the challenges facing the president's new approach to the Middle East based on shared values and common interests.

The administration remained as quiet as possible during the Iranian election season and in the days of street protests since Friday's vote. Incumbent Mahmoud Ahmadinejad has been declared the winner over his more reform-minded opponent, Mir Hossein Mousavi, by a margin opposition supporters have found impossible to believe.

As the Iranian government cracked down on demonstrations and reportedly detained dozens of opposition leaders, Vice President Biden said yesterday on NBC's Meet the Press that he had "doubts" about the election returns but that "we're going to withhold comment" until a more intensive review takes place in the coming days.

"There's an awful lot of question about how this election was run," Biden said, noting that the high urban turnout argued against such an easy victory for Ahmadinejad, whose conservative populism holds more appeal in rural areas. "I mean we're just waiting to see."

The cautious response illustrates the balance the administration is seeking between condemnation of what increasingly appears to be a fraudulent election and the likelihood that it will be dealing with Ahmadinejad after the dust settles.

The measured approach contrasts with some of the Bush administration's reactions to democratic challenges abroad. It also reflects the peculiar nature of Iran's democracy and what, if any, difference the winner of this presidential election means to U.S. interests in the region.

Iran's decisive political authority lies with Ayatollah Ali Khamenei, a Shiite cleric whose title is supreme leader. Such internationally pressing issues as Iran's nuclear program, which its leaders say is only for civilian power needs, falls under his purview.

But even within Iran's constrained democracy, which President Obama hailed last week for its robust debate, Ahmadinejad held some political legitimacy for winning the 2005 election. That vote was viewed as fair, even though the list of candidates was culled by Iran's religious leadership, as it was this time.

Questions surrounding Ahmadinejad's defeat of Mousavi - who favored greater rights for women, a more moderate tone in dealings with the West, and the maintaining of Iran's nuclear program - could make Obama's efforts to engage his government even more problematic.

Biden said yesterday that "talks with Iran are not a reward for good behavior." He indicated that negotiations should be pursued regardless of how the next few days unfold in Tehran.

"Our interests are the same before the election as after the election, and that is we want them to cease and desist from seeking a nuclear weapon and having one in its possession, and secondly to stop supporting terror."

But some Republicans, as well as Israel's government, say talks with a leader who has denied the Holocaust, threatened the Jewish state with annihilation, and called Iran's nuclear program nonnegotiable should be isolated. With accusations of fraud swirling around Ahmadinejad's victory, those hawkish voices are rising for Obama to change course.

On ABC's This Week yesterday, former Massachusetts Gov. Mitt Romney, a Republican, said: "What has occurred is that the election is a fraud, the results are inaccurate, and you're seeing a brutal repression of the people as they protest.

"The president ought to come out and state exactly those words, indicate that this has been a terribly managed decision by the autocratic regime in Iran."

In his speech to the Islamic world this month in Egypt, Obama noted that "in the middle of the Cold War, the U.S. played a role in the overthrow of a democratically elected Iranian government," and he recounted decades of subsequent hostility between the two countries.

"Rather than remain trapped in the past," he said, "I've made it clear to Iran's leaders and people that my country is prepared to move forward. The question now is not what Iran is against, but rather what future it wants to build."

Days later, Lebanese voters chose a coalition of pro-U.S. parties known as the March 14 alliance, rather than a movement led by the Islamist party Hezbollah, to form the next government.

The largely Shiite Muslim Hezbollah receives large amounts of financial support from Iran, and the election was the first pro-U.S. vote in the Middle East in years.

Whether Obama's overture to Muslims played a part - some analysts have said higher-than-expected turnout for the March 14 alliance may have been decisive - remains the subject of debate.

Iran's hard-liners, at least for now, are backing another term for Ahmadinejad. How the Iranian electorate responds will probably shape the Obama administration's next steps. For now, as Biden indicated, the administration is watching.