BEIRUT - U.S. support for a pair of diplomatic initiatives in Syria underscores the shifting views of how to end the civil war there and the West's quiet retreat from its demand that President Bashar Assad, step down immediately.

The Obama administration maintains that a lasting political solution requires Assad's exit. But facing military stalemate, well-armed jihadists and the world's worst humanitarian crisis, the United States is going along with international diplomatic efforts that could lead to more gradual change in Syria.

That shift comes along with other U.S. actions that Assad's supporters and foes take as proof Washington now believes that if Assad is ousted, there will be nothing to check the spreading chaos and extremism. U.S. warplanes now bomb the ISIL militants inside Syria, sharing skies with Syrian jets. U.S. officials assure Assad, through Iraqi intermediaries, that Syria's military is not their target. The United States still trains and equips Syrian insurgents, but now mainly to fight the Islamic State in Iraq and the Levant, not the government.

Now, the U.S. and other Western countries have publicly welcomed initiatives — one from the United Nations and one from Russia — that postpone any revival of the U.S.-backed Geneva framework, which called for a wholesale transfer of power to a "transitional governing body." The last Geneva talks failed a year ago amid vehement disagreement over whether that body could include Assad.

One of the new concepts is a U.N. proposal to "freeze" the fighting on the ground, first in the strategic crossroads city of Aleppo. The other is a plan from Russia, Assad's most powerful supporter, to try to spur talks between the warring sides at a meeting in Moscow later this month. Diplomats and others briefed on the plans say one Russian vision is of power-sharing between Assad's government and some opposition figures, and perhaps parliamentary elections that would precede any change in the presidency.

But the diplomatic proposals face serious challenges, relying on the leader of a rump state who is propped up by foreign powers and hemmed in by a growing and effective terrorist force that wants to build a caliphate. Many U.S. allies in the Syrian opposition reject the plans, and there is little indication that Assad or his main allies, Russia and Iran, feel any need to compromise. The U.S.-backed Free Syrian Army is on the ropes in northern Syria, once its stronghold, and insurgents disagree among themselves over military and political strategy.

And perhaps most of all, ISIL controls half of Syria's territory, though mostly desert, and it has managed to strengthen its grip even as the U.S. and its allies try to oust it from neighboring Iraq.

Still, Secretary of State John Kerry declared last week that the United States welcomed both initiatives. He made no call for Assad's resignation, a notable omission from Kerry, who has typically insisted on it in public remarks. Instead, he spoke of Assad as a leader who needed to change.

"It is time for President Assad, the Assad regime, to put their people first and to think about the consequences of their actions, which are attracting more and more terrorists to Syria, basically because of their efforts to remove Assad," Kerry said.

On Thursday in Geneva, Staffan de Mistura, the U.N. envoy for the crisis, also signaled a tactical shift, saying that such "new factors" as the growth of ISIL must be taken into account. He said there was no point in trying to organize a third round of Geneva talks before building unamabiguous support from both the Syrian government and its opponents for some kind of "Syrian political process."

The urgent search for a political solution, De Mistura said, must "bear in mind" not only the Geneva framework, "but also the need to adjust aspirations without preconditions, in line with the new factors …"

The shifts reflect a long-standing view among U.N. staff members in Syria that the West must adapt to the reality that Syrian insurgents have failed to defeat Assad.