Sako was one of few players to impress for the Molineux side last season when, after going into the year as one of the favourites to be promoted, they were relegated to the third tier of English football.
Jackett was appointed to try and get them back to the Championship at the first attempt, but he admits he may have to do so without attacking midfielder Sako, who scored nine goals last season.
The former Saint-Etienne player pleaded with the club to allow him to leave last week and Jackett confirmed to the Birmingham Mail that they are favourites to secure his services.
"Fulham are genuinely interested in Sako and now it is about negotiations between the two clubs," he said.
"As far as I know no fee has been agreed yet, but they are in negotiations. I don't know if it is close. The offer's at a very high level, whether it is at a point where the powers that be at Wolves want to accept that or not is another matter.
"He's not one I thought would necessarily be with us in League One at the start."
Jackett also revealed there could be further departures before the start of the season with keeper Dorus de Vries not training on Monday to talk with an unspecified Dutch club - he had talks with Roda JC last week.
He said there is also interest in transfer-listed players Roger Johnson, Jamie O'Hara, Stephen Ward and Karl Henry.
"There has been interest. Kevin Thelwell and Jez Moxey are mainly handling the negotiations on that front. There have been some enquiries, as you would imagine on July 1st, but nothing concrete that any of those are close to a move to any club," Jackett concluded.