According to a report from Sportitalia (via MilanLive), Milan must first try to sell Samu Castillejo in order to pursue the signing of a new right winger, with Chelsea rejecting any kind of loan for Hakim Ziyech.
Milan could try to sign a winger towards the end of the window, but in recent days, Leverkusen's Bailey has emerged as a top target.
However, the club's asking price is very high, and as a result, sales are needed in order raise funds for the transfer.
Bailey has a reported market value of €35 million (via transfermarkt.com), which could be quite a hefty fee for Milan, especially due to Financial Fair Play pressures on the Rossoneri right now.
It is very unlikely that Leverkusen will be willing to sell Bailey on loan with an option to buy, as they would want the funds immediately to find a replacement.
The 23-year-old winger had a very productive season, scoring 15 goals and providing 11 assists in 40 games in all competitions, as Leverkusen finished sixth in the Bundesliga, while they also suffered a surprise exit from the UEFA Europa league at the Round of 32 stage.
With Milan now in the UEFA Champions League, they will be keen to add to their quality in attack, and upgrading from Castillejo to Bailey would definitely be of major benefit to the Rossoneri for the coming season.