Rangers legend Barry Ferguson insists Douglas Park must splash the cash to stop Celtic's charge for 10 in a row.
He believes the new interim chairman will need to open the chequebook in order to divert the flow of silverware away from the other side of Glasgow.
The Hoops sealed a ninth successive Premiership crown after the top flight was called to a premature end on Monday.
Steven Gerrard’s Rangers, who had a game in hand, finished 13 points adrift of their bitter rivals after suffering a league collapse after the winter break.
Ferguson won of five titles across his two spells with the club and he now believes Park, who replaced Dave King in the role in March, must push the boat out during the summer transfer window in a bid to close the gap on Neil Lennon’s team.
Speaking to PLZ Soccer, he said: “It’s definitely a bonus with the new (Castore) kit deal, £25 million coming into the club.
“I think in terms of transfer fees for players, I think that will come down because of the way the world has gone.
“I think Douglas Park will invest, I don’t know exactly how much. I think he will invest in the manager and give him some funds to go and strengthen.
"I do think Rangers will need to strengthen.
“He (Gerrard) has to bring something back to Ibrox. When you’re at a club like Rangers there are demands and expectations and the fans want to see silverware coming to Ibrox at some stage, and I do believe he is the right guy to do that.
“I do believe he has a very good chance of doing that next season.
“That might come down to Douglas Park having to invest a bit more money than he would like, but I’m sure he will put his trust in the manager to do that.
“This is where it will be important in the transfer window. You know the demands and expectations that are placed on the Rangers players and management’s shoulders, he has to get it spot on.”
Rangers, who had played one less game at that point, ended 2019 just two points behind leaders Celtic with a game in hand, after beating their fierce rivals 2-1 at Parkhead on December 29.
But they failed to maintain their domestic form following the three-week shutdown, losing to Hearts, Kilmarnock and Hamilton in the league.
Ferguson insists Gerrard also needs to sign players with proven winning mentalities.
He added: “It was evident when they came back off the winter break. I saw some games with Celtic when I didn’t think they played particularly well but they got the three points, and that’s what you need to do to win championships and win trophies.
“It’s not always about about playing good football.
“When you go to places like Tynecastle, even at home to Hamilton Accies, you’ve got to find a way of doing that and I think that’s where the manager will realise that he needs maybe two, three, four players in with that sort of mentality.
“I do believe there are good players at Rangers but I think he needs to add guys who can handle it.
“When you come back after the winter break, that’s the business end of the season.”
