Wagner, a German national, will see his contract with the Union expires at the end of the year, though the club have the option of extending it by another year.
Current Leeds midfielder Brenden Aaronson and Wagner were team-mates at Subaru Park from 2019 until Aaronson’s departure for Red Bull Salzburg.
Leeds were linked repeatedly with wanting to sign Wagner over the course of the summer transfer window, but they did not pull the trigger on a bid.
However, it is suggested that Leeds do presently have real interest in the 25-year-old defender, who they could try to sign in January.
The German has made 31 appearances in all competitions for Philadelphia Union this campaign, recording six assists and earning five cautions along the way.
Leeds currently have Pascal Struijk playing as a makeshift left-back following Junior Firpo’s long-term injury and might well add a specialist option to their squad in January.
The Whites are currently in ninth place in the Premier League table and will play host to promoted Nottingham Forest on Monday night, hoping to end a run of three league games without a win.
