An agreement on powersharing among four Afghan factions is close as the talks run into their ninth day.
UN envoy Lakhdar Brahimi has been meeting the factions separately.
He is aiming to set up 29 Cabinet posts for a new interim administration from 150 candidates.
Delegates and observers at the talks near Bonn, Germany, say the factions have agreed the interim premier will be Hamid Karzai, a leading anti-Taliban commander who is fighting near Kandahar.
UN spokesman Ahmad Fawzi, said: "The parties have made progress toward whittling down the list and agreeing on the head of the interim administration.
"We await a meeting of the four groups to ratify the final shortlist. That includes confirming Karzai. This is a very difficult hurdle."
A consensus on the Cabinet could trigger a speedy transfer of power in Kabul - with December 22 envisaged as a target date - and secure billions in promised aid to reconstruct the country.