US President Joe Biden is expected to decide as soon as Tuesday on whether to extend an Aug. 31 deadline to airlift Americans and their allies to safety.
This comes as thousands of desperate Afghans and foreigners massed at Kabul's airport in the hope of fleeing Afghanistan's new Taliban rulers.
Biden warned on Sunday that the evacuation was going to be "hard and painful" and much could still go wrong. US troops might stay beyond an Aug. 31 deadline to oversee the evacuation, he said.
On Monday, an administration official told Reuters that Biden would decide within 24 hours whether to extend the timeline to give the Pentagon time to prepare.
Department of Defense officials said it would still take days to fly out the 6,000 troops deployed to secure and run the airlift, beyond the need to remove thousands of Americans, citizens of allied countries and Afghans who worked with US forces.
Also, the Western countries worked at a "war-footing pace" on Tuesday to get people out of Afghanistan, a NATO country diplomat said, as US President Joe Biden looked set to come under pressure from other G7 leaders to seek more time to complete the airlift.
Widespread chaos punctuated by sporadic violence has gripped Kabul's airport, with Western troops and Afghan security guards driving back crowds desperate to flee following the Taliban's takeover of the Afghan capital on Aug. 15.
Countries conducting the evacuations are trying to meet a Aug. 31 deadline agreed earlier with the Taliban for the withdrawal of foreign forces, a NATO diplomat told Reuters.
"Every foreign force member is working at a war-footing pace to meet the deadline," said the official, who declined to be identified.
Democratic US Representative Adam Schiff, chairman of the House of Representatives Intelligence Committee, told reporters after a briefing on Afghanistan by intelligence officials that he did not believe the evacuation could be completed in the eight days remaining.
"I think it's possible but I think it's very unlikely given the number of Americans who still need to be evacuated," Schiff said.
A Taliban official said on Monday an extension would not be granted, though he said foreign forces had not sought one. Washington said negotiations were continuing.