WASHINGTON — So now all Republican political calculations come down to one question: Will it be possible to successfully criticize a candidate whom even Hillary Clinton, the toughest partisan in American politics, could not wound?

Barack Obama will not be defeated by taunts about his middle name, which gain his juvenile persecutors all the sympathy of a schoolyard bully.

He will not be defeated by sinister interpretations of his hypnotic popularity. People generally — and unsurprisingly — are attracted to the handsome, genial and eloquent. And in a change election, Mr. Obama will not be defeated because he seems inexperienced — his freshness is actually a qualification.

But Mr. Obama may be defeated in the end because he is inexperienced — because he has already made some serious errors in the primaries that will exact a cost in the general election.

As a thought experiment, consider the foreign policy achievements of Mr Obama’s first 100 days.

Redeeming his inaugural pledge to “pay any price, bear any burden, fly any distance to meet with our enemies,” Mr. Obama’s first major international meeting is with President Ahmadinejad of Iran. National security adviser, Samantha Power, does her best to talk tough on human rights in preparation for the meeting.

But, as Henry Kissinger once said “When talks become their own objective they are at the mercy of the party most prepared to break them off.” Having made Iranian talks “without precondition” his major foreign policy goal, Mr Obama is left with little leverage to extract concessions, and little choice but to move forward.

The New York Post runs a front-page picture of the Obama/Ahmadinejad handshake under the headline “Surrender Summit!” The story notes another of Mr. Obama’s historic firsts: the first American president to meet with a Holocaust denier. The Israeli prime minister publicly asks, “Why is the American president meeting with a leader who calls us ‘filthy bacteria’ and threatens to wipe us ‘off the map’?” Tens of thousands protest in Tel Aviv, carrying signs reading “Chamberlain Lives!”

America’s moderate Arab allies in the region also feel betrayed, assuming that America is cutting a bilateral deal with Iran that accepts its nuclear ambitions, while leaving the Sunni powers out in the cold. The Egyptian press notes that President Obama’s motorcade in Tehran passed near a street named in honor of Khaled Eslamboli, the assassin of former Egyptian president, Anwar Sadat.

Shell-shocked by the criticism, the Obama administration moves its forthcoming presidential summit with Raul Castro to the Turks and Caicos, in a vain attempt to limit press scrutiny. The four-minute, Friday evening meeting — photographers are forbidden — still results in hundreds of thousands of Cuban protesters in Miami. Spouses of the imprisoned and tortured carry pictures of their loved ones. President

Chavez of Venezuela praises Mr. Obama’s visit as a “public apology for generations of American imperialism and militarism.”

At the same time, the Obama administration is arm-twisting Mexico and Canada into a renegotiation of the North American Free Trade Agreement. The Mexican president wonders aloud to the press: “Why is the new president courting his enemies in the hemisphere while insulting his closest friends?”

Mr. Obama’s Oval Office speech to the nation on Iraq is initially more successful. As promised, he orders a phased, unconditional withdrawal of combat forces, beginning “not in six months or one year — now.” American troops will no longer be embedded in Iraqi combat units or used to combat Iranian influence (all pledges made during his campaign).

Many Americans cheer. But the next day, the Washington Post records stunned disbelief among the troops. A high-ranking officer observes, “The surest way to break the morale of the military is to undo its achievements and humiliate it on the verge of success.” Egypt, Saudi Arabia, and other Sunni allies react with panic at another sign of American unsteadiness and retreat from the region. Armed groups of Sunni and Shiites within Iraq begin preparing for a resumption of sectarian conflict. An intercepted Al Qaeda communication talks of “so much defeat, exhaustion and death — and then, praise be, this unexpected victory!”

Mr. Obama’s 100-day agenda would be designed, in part, to improve America’s global image. But there is something worse than being unpopular in the world — and that is being a pleading, panting joke. By simultaneously embracing appeasement, protectionism, and retreat, President Obama would manage to make Jimmy Carter look like Teddy Roosevelt.

Which is why President Obama would probably not take these actions — at least in the form he has pledged. Sitting behind the resolute desk is a sobering experience that makes foolish campaign promises seem suddenly less binding.

But it is a bad sign for a candidate when the best we can hope is for him to violate his commitments. And that’s a good sign for John McCain.