Former Rangers captain John McClelland has told the Ibrox board that they must splash the cash if Steven Gerrard becomes their new boss in order for him to have a chance of stopping Brendan Rodgers leading Celtic to a record-breaking 10 league titles in succession.
Rangers are currently without a manager after Graeme Murty's departure on Tuesday morning and Liverpool legend Gerrard is in talks with the club about the role.
Northern Ireland World Cup hero McClelland has suggested it would be a massive boost for his old club to appoint the ex-England captain.
However, McClelland is adamant the job could only work for Gerrard, currently in charge of Liverpool's Under-18s, with major financial backing to compete with Celtic, who won their seventh championship in a row on Sunday with a thumping 5-0 victory over Rangers at Parkhead.
"There is no doubt that having a figurehead like Steven Gerrard would give the club a massive boost, but it would only be the first boost," said McClelland, a defender with Rangers in the early '80s.
"Is he, or any manager for that matter, going to get the complete support he deserves? Whoever comes in will have to be given a big investment to challenge Celtic. They need a major capital outlay to push forward.
"If Steven Gerrard does take over, one of his remits would be to stop Celtic winning the 10 in a row. It is unrealistic to think that it could be done in a season.
"With the right backing it would take a couple to compete. He would have to get a few established players in who he could really rely on and then take it from there.
"You want to show progress and show what you are building, do well in some of the cups, get the standards up and then you could really challenge for the title.
"Brendan Rodgers had a good base when he took over but has done a great job, and Celtic are like a runaway train, so it will be tough for Steven Gerrard or whoever takes over to stop them."
McClelland, who captained his country under Billy Bingham, added: "When Graeme Souness was made Rangers manager and got them on the road to nine titles in a row, Celtic were more at the races than Rangers are at the moment.
"Even Celtic at that time had to throw money at it to stop Rangers doing 10 in a row," stated McClelland, who added that it would be vital for Gerrard to bring an experienced assistant with him should he take the Ibrox reins.
That is likely to be ex-Liverpool and Scotland midfielder Gary McAllister, a team-mate of McClelland's in Leeds United's 1992 English league title-winning side.
"It can intimidate any sort of manager that takes over a club the size of Rangers," said McClelland, who won 53 caps. "If you hit the ground running it has a rollerball effect and it can continue but if you hit the ground and stumble at the start then the pressure comes on you very quickly."
Gerrard's good friend Danny Murphy said: "The truth is there's nothing definitive. He has had talks and they were positive. He's got more talks this week.
"He's a really ambitious guy Stevie, but he's also bright and I don't think he's going to put himself into a position where he walks into a job with his hands tied in terms of the resources he's got to compete with Brendan.
"I think he's probably needing some more reassurances."
The club's latest financial figures showed they had received £17.7m in interest-free loans from shareholders and other investors by the turn of the year, at least some of which they plan to turn into equity.
They also received a short-term external loan, reported to be £3m, and concrete plans for a proposed income-raising share issue have not yet materialised.
Gerrard will press the board over the finances available should he take over a club third in the Premiership and level on points with fourth-placed Hibs.