Democratic presidential contender Bill Richardson believes the United States must reach out to moderate elements in Iranian society if it is to defuse a standoff between the two countries over Iran's pursuit of nuclear weapons.

The New Mexico governor, previewing a speech he was to deliver later Wednesday in Washington, said after a Boston fundraiser: "You start first with mediation, with diplomacy, with building international support for your goals, possibly sanctions. The good news is that Iran's nuclear weapon development is maybe three to four years away, so there is time."

Richardson, a former U.N. ambassador under President Clinton, said he would not seek immediate face-to-face negotiations with Iranian President Mahmoud Ahmadinejad, a hard-liner elected in 2005, but with others around him.

"I would not pursue him first," said Richardson, who has used his negotiating skills on a number of foreign rescue missions over the past two decades on behalf of Americans held prisoner. "I would pursue other moderate clerics. I would pursue students, would pursue business leaders. I would pursue moderate elements in the foreign ministry like former Foreign Minister (Kamal) Kharazi, who I know. I believe there's a potential for dialogue."

The Bush administration has rejected direct negotiations with Ahmadinejad and has instead pursued international economic sanctions to stop the country's nuclear weapons development.

Meanwhile, nearly all the Republicans vying to replace President Bush said during a recent debate they would not rule out using nuclear weapons to halt the program. Vice President Dick Cheney has repeatedly said the administration is keeping all options on the table for dealing with Iran, even as efforts continue to resolve the dispute diplomatically.

"I thought it was incomprehensible," Richardson said on the eve of another debate between the Democrats, also in Washington. "The Republican debates, all I hear is how we're going to shut down this country to immigrants, how we're going to expand the use of torture such as waterboarding and how we're going to continue on this disastrous Iraq policy. The Republican Party, the Republican candidates, are a party of the status quo. They don't want to change and this country is changing."

Among the other Democratic presidential candidates, front-runner Hillary Rodham Clinton is also scheduled to give a foreign policy speech Wednesday, to the Center for New American Security in Washington.