The moderate political and military command structure the U.S. has been trying to foster within the Syrian opposition appears to be fracturing, a victim of bitter Arab regional rivalries.

The regional tension splitting the Syrian rebel movement is between Qatar and Turkey, on one side, and Saudi Arabia, Jordan and the United Emirates on the other. The former group would like to see an Islamist government headed by the Muslim Brotherhood after the fall of President Bashar al-Assad. The latter group opposes any expansion of Muslim Brotherhood influence into Syria, fearing that the movement could spread from there to endanger Jordan, Saudi Arabia and the U.A.E.

The Obama administration, to the consternation of some of its Arab allies, has been somewhere in the middle, resisting the efforts of Qatar and Turkey to impose their proxies, but not doing so very effectively. The lack of U.S. influence is one more sign of the price that Washington has paid in coming to the Syria problem so late, and so feebly.

The battle for political influence has centered around the opposition’s appointment of Ghassan Hitto as interim prime minister on March 19, under political pressure from Qatar and Turkey.

Though Hitto is a U.S. citizen who until recently lived in Texas, some Arab critics argue that he is sympathetic to the Islamist line pushed by Doha and Ankara. Robert Ford, the U.S. ambassador to Syria and an informal coordinator of U.S. policy, told a House panel last Thursday that Hitto is “more Texan than Muslim Brotherhood.” This comment seemed to imply U.S. support, but one key U.S. official is said to have told colleagues that Hitto’s appointment as interim prime minister caught the U.S. by surprise.

Hitto’s appointment was sharply rejected by the Syrian opposition leadership the U.S. has been cultivating. First came the resignation Sunday of Sheikh Moaz al-Khatib, the head of the opposition coalition and seemingly a U.S. favorite when he met in Munich early last month with Vice President Joe Biden. Then Gen. Salim Idriss, who claimed the title of commander of the Free Syrian Army last December, told colleagues that he and his commanders couldn’t support Hitto until a broader array of the opposition had agreed to back him.

These dissents against Hitto could, of course, be withdrawn when the Arab League meets in Doha Tuesday — in the sort of patched-together compromise that so often characterizes inter-Arab diplomacy. There’s talk, for example, that Hitto could be replaced as interim prime minister by Burhan Ghalioun, a Syrian opposition leader who has good relations with both Saudi Arabia and Qatar. But the underlying tensions will continue.

What’s happening here, in part, is that Saudi Arabia and Qatar are conducting a decades-old battle for influence, using their contacts in the Syrian opposition as proxies. The two wealthy Gulf nations use their media outlets — al-Arabiya for Saudi Arabia and al-Jazeera for Qatar — to promote their different agendas. It’s a ruinous rivalry, reminiscent of the way Arab regimes once sponsored feuding warlords in Lebanon.

The biggest surprise is how little the U.S. has been willing or able to influence the Syrian political maneuvers in recent months. U.S. frustration with the old Islamist-dominated opposition led to the creation last fall of a new umbrella organization, headed by Khatib. But it’s mostly been downhill since then.

Washington tried two weeks ago to head off appointment of a prime minister. The U.S. proposed that instead of asking the Arab League to recognize an interim government, led by a prime minister, the League should grant recognition to a small “executive authority” headed by Khatib. That approach was endorsed by Britain, France and Germany; but under Qatari and Turkish pressure, this moderate plan was swept aside.

Frederic Hof, who until recently was the U.S. special adviser for transition in Syria, said in a telephone interview from Europe Monday that internecine opposition politics were a sign that the U.S. should support a serious transitional government on the ground inside Syria and “get away from the pushing and shoving of an opposition movement.” Without such a substantial goal, he said, “the trivial will trump the important every time” in opposition debates.

Critics of President Obama’s low-key approach to Syria would argue that the opposition wrangling illustrates what happens when the U.S. leaves policy to headstrong allies, such as Turkey and Qatar. The White House could counter that opposition fracas shows what a mess Syria is—and why the U.S. is wise to keep its distance.

The dangerous aspect of the ascendency of Qatar and Turkey is that they are driving the Arab revolutions further toward Islamist governance. “Do you want to hand post-Bashar Syria to the Muslim Brotherhood?” asks one prominent Arab diplomat. Like many in the Arab world, he fears that the Brotherhood is now inexorably on the march toward regional hegemony.

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