NATO's supreme commander, U.S. General Joseph Ralston, is reporting to the alliance's ruling council in Brussels on the findings of his visit to Macedonia Monday.
NATO officials say it is not likely that the ambassadors will decide on deployment Tuesday. They are expected to discuss General Ralston's findings and act later in the week.
Analysts say there is dissent within NATO over the mission, with some fearing that it could pull the alliance into another long deployment in the Balkans.
NATO has said it will deploy a 3,500 member force to Macedonia when it believes a sustainable cease-fire is in place.
The NATO force is to gather and destroy weapons that are collected by the rebels and left at pre-arranged sites in a limited 30-day operation called "Essential Harvest." NATO already has a 400-member advance team in place.
NATO hopes to build on a political momentum that started following the signing of a peace agreement between Macedonia's leading political parties earlier this month.
The rebels say they are fighting for more rights for Macedonia's ethnic-Albanian minority, which makes up about one third of the country's population.