WASHINGTON — To rein in Tehran’s nuclear ambitions, Mitt Romney says he would conduct naval exercises in the Persian Gulf to remind Iran of American military might. He would try to ratchet up Security Council sanctions on Iran, targeting its Revolutionary Guards, and the country’s central bank and other financial institutions. And if Russia and China do not go along, he says, the United States should team up with other willing governments to put such punitive measures in place.

As it turns out, that amounts to what President Obama is doing.

As their tone on Iran escalates in advance of appearances via satellite Tuesday morning before the country’s most influential pro-Israel lobbying group, the Republican candidates for president have tried to draw stark contrasts between themselves and Mr. Obama when it comes to stopping Iran from getting a nuclear weapon. Mr. Obama’s Iran strategy, Rick Santorum said recently on “Meet the Press” on NBC, risked turning the United States into a “paper tiger.” Newt Gingrich said that on Iran, “we’re being played for fools.”

On Sunday, Mr. Romney, appearing in Atlanta, offered this: “If Barack Obama gets re-elected, Iran will have a nuclear weapon.” And on Monday, he wrote an op-ed article in The Washington Post comparing Mr. Obama to President Jimmy Carter, who he said “fretted in the White House” as Iran held American hostages for 444 days.

Mr. Obama and his backers have cried foul, saying the Republican candidates, in the quest to appear tough, are playing a dangerous game that could end up driving Iran closer to a nuclear weapon, as Mr. Obama implied in his own address Sunday to a pro-Israel group, the American Israel Public Affairs Committee.