The Tannadice boss was close to signing the 25-year-old Republic of Ireland international from St Mirren when he was in charge of Hibernian last August before a last-minute snag on deadline day prevented the transfer from happening.
McGrath ended up joining Wigan in January but has struggled for game time with the Latics and is now set to join United on a season-long loan.
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“It’s a deal we would hope to conclude but haven’t done so as yet, so difficult for me to comment on properly,” said Ross, speaking at his pre-match press conference ahead of Thursday’s Europa Conference League qualifier at home to AZ Alkmaar.
“But certainly in terms of our desire to bring that player to the club, that is there.
“I think that’s common knowledge now and I’m confident that hopefully that will be the case.”
Ross thought he had signed McGrath from St Mirren 11 months ago in a proposed swap deal with Scott Allan before a paperwork mix-up at the Easter Road club’s end killed the transfer.
The manager was sacked by Hibs in December but has continued to monitor the midfielder from afar.
“When you work with players or identify them as players you would like to work with, you continually follow their career pathway and how they’re getting on,” said Ross.
“He’s somebody I’ve been keen to work with in the past and hopefully I’ll get that opportunity soon.”