Smith said he wanted to protect "everything magical" about Rangers and to place the club into "the hands of Rangers people".
He was backed by a number of top Scottish businessmen including the multi-millionaire chairman of Clyde Blowers Jim McColl, and Lanarkshire bus tycoon Douglas Park.
Smith made his dramatic intervention after a meeting at which a Company Voluntary Arrangement was formally rejected and the liquidation of the 140-year-old Govan club became inevitable. Green then bought the club's assets for £5.5million.
Smith said: "I can confirm that following talks over the last few weeks I am leading a new bid for Rangers Football Club.
"I have been assisted by Jim McColl, Douglas Park and other prominent Scottish businessmen with a shared objective – that Rangers Football Club should be in the hands of Rangers people who will stabilise the club and protect it from future situations like we find ourselves in today.
"With this in mind, representatives have, on behalf of my group, made representations to BDO, Duff and Phelps and indeed Charles Green, notifying them of our willingness to offer on the 'newco' basis on which Mr Green is proceeding.
"We would call on Mr Green to step aside and allow us to proceed with our deal which is in the best interests of the creditors, the employees, the fans and other stakeholders of Rangers Football Club.
"None of our group has any desire to own Rangers Football Club but we have put this deal in place to save the club.
"However, our overriding objective is to ensure that the stadium, the history and everything else magical about Rangers Football Club is protected and nurtured back to good health and provide a platform for Rangers for generations to come.
"Let's be clear, this is an acquisition designed to stabilise the club and ensure history does not repeat itself.
"We are not in this to take money out of the club but more so to do whatever it takes in a turnaround plan to ensure within a few years the club can be passed on intact and to the right people. The supporters should be under no illusion that it will be extremely hard but with their support we can overcome financial hardship that lies ahead by lending their support to what we feel is the correct way forward – for Rangers people who know the club inside and out to control its destiny.
"The prominent Scottish businessmen involved have agreed to provide acquisition funding to allow myself and a management team to take on Rangers Football Club and make the business self-sufficient, with long-term sustainability essential.
"I would hope that this offer is fully supported by everyone in the Rangers Family as without them the club cannot and will not survive. We therefore want to ensure honesty and transparency in everything we do. We want to rebuild Rangers Football Club and in doing so return the institution to the standards it is known for."
If his bid is successful, Smith will be chairman of Rangers and involved in appointments to an entire new corporate governance structure.
Ally McCoist, whose future has been in doubt in the past 24 hours, would remain as the Ibrox manager. Smith would have an influence in all appointments, with assistance from Park and McColl.
As a matter of urgency, a chief executive will be sought, and he would join Smith in negotiations with the SPL and the SFA on the newco Rangers' place in the Scottish game and all possible sanctions.
While Smith will not be involved in the day-to-day running of the business, he will oversee the complete rebuilding of Rangers as a football club.
The £6m is not a loan but a capital injection, with Park, McColl and other Rangers-supporting businessmen prepared to fund any working capital until season ticket revenue is gathered. A share issue will also be launched in the medium-term.
A Rangers Supporters Assembly spokesman said: "Despite numerous assurances from Duff & Phelps that a successful CVA was achievable, it seems a "Newco" was always their preferred option.
"The Rangers Family has suffered one of the most horrendous periods in our history and as the key stakeholders in the Club, the supporters are desperate for positive news and hope to hear much more in coming days."
Meanwhile, Green moved to quash speculation about McCoist.
He said: "Our consortium wants Ally McCoist to remain as manager and we firmly believe he is the man to take Rangers forward. He embodies everything that is great about the club and without question we want him to continue as the Rangers manager.
"I fully understand that other people have courted Ally who do not wish to see us succeed but, I believe time for rancour is over now that the club has been sold and every-one with the inter-ests of Rang-ers at heart should unite."