Iran nuclear standoff roils U.S. campaign

By Steve Holland

WASHINGTON (Reuters) - Iran's nuclear program and its role in Iraq are roiling the U.S. presidential campaign with Democrats squabbling over tactics and Republicans warning of the possibility of military force.

All the major candidates from both parties have said an Iran with nuclear weapons is unacceptable and have pointedly kept the military option on the table out of concern for Israel's security and to prevent a regional war.

And they are all insisting that diplomacy be exhausted and sanctions pursued before any military strikes are considered. The difference lies in emphasis.

Republicans trying to appeal to conservative voters are far more aggressive on the possibility of military action to prevent Iran from becoming a nuclear state.

"They are not going to be allowed to become a nuclear power -- it's just not going to happen," said Republican front-runner Rudy Giuliani said.

Democrats are more open to direct talks with Tehran, which President George W. Bush has refused.

"No one has an incentive to be perceived as being soft on Iran," said Will Dobson, managing editor of Foreign Policy magazine. "But you see in the Democratic camp at least an attempt to distinguish themselves from President Bush."

The Democratic front-runner, New York Sen. Hillary Clinton, is being accused by rivals Illinois Sen. Barack Obama and John Edwards of giving Bush cover to launch a pre-emptive strike by voting for a Senate resolution that recommends the State Department declare Iran's Revolutionary Guards a terrorist organization.