Townsend, on loan from Tottenham, has opted to cut short his stay at the club and Delph has returned to parent club Aston Villa after being been ruled out for the rest of the season with an ankle injury sustained in the recent defeat at Coventry.
Winger Robbie Rogers is also doubtful after suffering concussion. The USA international was stretchered off shortly after making his first appearance for the club in last weekend's win over Doncaster.
Defenders Paul Connolly and Leigh Bromby, midfielder Lloyd Sam and forwards Ramon Nunez and Billy Paynter are among those who could return to contention after featuring in a behind-closed-doors friendly with Hull this week.
Warnock, who has no other new injury or suspension worries, will want to launch his tenure at Elland Road with victory to keep his side in touch with the play-offs.