Daly was substituted during injury-time in the narrow 2-1 victory over Arbroath at Gayfield on Saturday and is now a serious doubt for the final.
The Irishman, who netted his 25th goal of the season against the Red Lichties, suffered a hamstring strain in his right leg and came off as a precaution.
Medical staff at Murray Park are monitoring the 31-year-old's fitness and are hopeful he will be able to take to the field against Raith this Sunday. Daly, the hugely-experienced former Dundee United player, has been one of the mainstays of Ally McCoist's side during the 2013-14 campaign. And it would be a devastating blow to Rangers, who are chasing an unprecedented treble, if he is ruled out of the final showdown with Rovers.
But Light Blues midfielder Kyle Hutton is confident his team-mate will be in the starting line-up for the meeting with the SPFL Championship club.
He said: "Knowing how big Jon is, he will be in the team for the final come Sunday. Big Jon would probably play with a broken leg if he could.
"It wasn't good to see him go off towards the end of the Arbroath game.
"All of the boys are keeping their fingers crossed that he will be okay to play against Raith in the cup final as he is such an important player for Rangers.
"I think that only big Jig (Rangers captain Lee McCulloch) has played in more games for us than Jon this season. That tells you everything you need to know about him.
"We all look after ourselves well at Rangers. Jon is no different. He is a top professional who lives his life right and looks after his body properly.
"That is why he is a player at Rangers and why he has played so many games for the first team this season and has scored so many goals for us as well.
"He is in his thirties now, but he has taken part in most of the matches that we have played. To do that at his age says a lot about his professionalism."
Hutton added: "Jon is a great guy to have about the place and it would be important to our chances of winning the final if he is available to play.
"He scores goals and sets up chances for those around him.
"We have the Scottish Cup game against Dundee United after the cup final and I am sure he will want to be involved in that given that it is his former club. I am sure he will be fit to play."