VIENNA, Austria (AP) – He’s running unopposed, but Mohamed ElBaradei may still fail in his bid for a third term leading the U.N. nuclear watchdog agency, tripped by his main opponent, the United States.

Unable to find a candidate willing to oppose the independent-minded Egyptian diplomat, Washington is now quietly lobbying other member states in ElBaradei’s International Atomic Energy Agency in a bid to unseat him by June, opening the way for a replacement more to the Bush administration’s liking – one harder on Iran and other nations on the U.S. nasty list.

With the agency spearheading international attempts to squelch nuclear proliferation, who controls the IAEA is key for Bush administration officials. They want someone sharing their view of which country represents a nuclear threat and what to do about them.

ElBaradei has challenged those views – particularly over prewar Iraq and Iran, both labeled part of an “axis of evil” with North Korea by President Bush.

He first disputed U.S. assertions that Saddam Hussein had an active nuclear weapons program – claims that remain unproven.

He then refused to endorse assertions by Washington that Iran was working to make nuclear weapons. Tehran says its nuclear program is for generating electricity.

A direct U.S. attempt to unseat ElBaradei fizzled late last year, with the Americans unable to find anyone to challenge him for a third term by the Dec. 31 deadline, shortly after the Bush administration called on him to step down after completing a second term this summer.

Since then, the nuclear power struggle has moved underground, but even before Dec. 31 much of it was cloak and dagger, including reported U.S. wiretaps of ElBaradei’s phone conversations in attempts to show he was demonstrating favoritism toward Iran in his investigation of its nuclear activities.

This is not the first U.S. campaign against heads of U.N. organizations deemed at odds with American foreign policy.

Jose Mauricio Bustani was voted out of office as director general of the Organization for the Prohibition of Chemical Weapons in April 2002 after Washington accused him of mismanagement and rallied other countries in a vote to have him dismissed.

At the time, Bustani’s supporters said Washington wanted him removed not because he performed poorly but because he supported making Iraq a member of his organization, which might have interfered with U.S. plans for war in Iraq.

U.S. officials in Vienna and Washington refuse to discuss Washington’s strategy in toppling ElBaradei. But diplomats accredited to the Vienna-based IAEA say America has a new candidate in the wings, who will be presented if the United States swings enough nations on the IAEA board of governors to back its demand for a no-confidence vote in the incumbent.

“They’ve already started lobbying in the capitals,” one diplomat told The Associated Press on condition of anonymity. “Whether or not they call for a (no-confidence) vote depends on the support they will get.”

ElBaradei himself appears to be taking the campaign to oust him in stride.

“Member states have asked me to continue to serve,” he told the AP. “I see that as confidence in my stewardship.”

Agency officials close to the soft-spoken and austere diplomat say that privately he is of two minds about what they describe as an occasionally nasty U.S. campaign.

“His reaction was: ‘This is old news. Why do we have to dignify this with a response?”‘ said one, when asked about ElBaradei reaction to revelations of his phone calls being bugged. “On the other hand, from a personal standpoint it bothers him” that his conversations with family members are being monitored.

To oust ElBaradei, Washington must find backing from 12 other member nations of the 35-nation IAEA board of governors. It already can count on traditional allies Canada and Australia and several others, and diplomats say it hopes to sway enough others from Europe to get the required number.

The key players include former Soviet bloc nations like Hungary, Poland and Slovakia, all board members with strong post-communist loyalties to Washington and which supported the U.S. campaign in Iraq.

“We expect to be approached in the course of the next few weeks,” said a diplomat from one of those countries, without divulging his nation’s stance.

Other potential supporters are West European countries now sitting on the fence on whether to back ElBaradei.

“He continues to enjoy our confidence but we support the principle that heads of U.N. organizations should sit only two terms,” said a West European diplomat in a hedge referring to informal consensus among the top nation-contributors to U.N. organizations.

Also crucial is who Washington has waiting in the wings. With candidates from nuclear weapons stations unwanted in the job, he is unlikely to be American, and diplomats say they are skeptical that the Bush administration can put forward anyone who will find broad acceptance from what is generally an America-skeptic IAEA board.

A wild card, played Friday, was the announcement from Washington that U.S. Undersecretary of State John Bolton was being replaced. Bolton, an administration hawk, was considered the chief architect of the anti-ElBaradei campaign.