Former members of Annan’s negotiating team say that after then-Secretary of State Hillary Rodham Clinton and Russian Foreign Minister Sergei Lavrov on June 30, 2012, jointly signed a communique drafted by Annan, which called for a political “transition” in Syria, there was as much momentum for a deal then as Kerry achieved a year later on chemical weapons. Afterward, Annan flew from Geneva to Moscow and gained what he believed to be Russian President Vladimir Putin’s consent to begin to quietly push Assad out. But suddenly both the U.S. and Britain issued public calls for Assad’s ouster, and Annan felt blindsided. Immediately afterward, against his advice, then-U.N. Ambassador Susan Rice offered up a “Chapter 7” resolution opening the door to force against Assad, which Annan felt was premature.

Annan resigned a month later. At the time, the soft-spoken Ghanaian diplomat was cagey about his reasons, appearing to blame all sides. “I did not receive all the support that the cause deserved,” Annan told reporters in Geneva. He also criticized what he called “finger-pointing and name-calling in the Security Council.” But former senior aides and U.N. officials say in private that Annan blamed the Obama administration in large part. “The U.S. couldn’t even stand by an agreement that the secretary of State had signed in Geneva,” said one former close Annan aide who would discuss the talks only on condition of anonymity. “He quit in frustration. I think it was clear that the White House was very worried about seeming to do a deal with the Russians and being soft on Putin during the campaign.” One of the biggest Republican criticisms of Obama at the time was that he had, in an embarrassing “open mike” moment, promised Moscow more “flexibility” on missile defense after the election.

Administration officials deny this account, as do some who were involved at the State Department. Nonetheless, Frederic Hof, a U.S. ambassador who was Clinton’s special adviser for transition in Syria at the time, agrees that the negotiations could have been better handled. The harsh demand that “Assad must go” voiced by Clinton and British Foreign Secretary William Hague was “gratuitous,” says Hof, a senior fellow at the Atlantic Council. “Perhaps a greater effort should have been made to give Annan the time to do his due diligence.” Still, Hof says he saw no evidence that the administration was posturing for political reasons.

A current senior State Department official concedes that one of the problems with making the Annan communique work may have been Clinton’s distaste for getting involved in extended direct mediation, in dramatic contrast to her successor, who has opened up negotiations on several fronts at once—with Syria and the Russians, with Iran, and between the Palestinians and Israelis. “We’ve made more trips to the Mideast in the last nine months than she made in four years,” says this official.