Sunderland are trying to sign Aston Villa forward Ross McCormack on loan, Sky sources understand.
But any potential deal for the 31-year-old forward is being held up by Villa's protracted talks over signing West Ham's Robert Snodgrass.
Snodgrass is in advanced talks over a loan of his own to Villa Park, despite additional interest from both Sunderland and Birmingham City.
Sky Sports News understands Villa are determined to get Snodgrass through the door before allowing McCormack, who signed from Fulham in 2016, to leave.
Snodgrass worked with Villa manager Steve Bruce at Hull City before Bruce resigned last summer and Snodgrass moved to West Ham in January.
His potential replacement McCormack was a £12m signing from Fulham but he has not settled at the West Midlands club and only made 23 appearances.