"We believe that the structure of the bid from Mr. Miller provides not only the most deliverable outcome but preserves the history of the club," said Paul Clark, one of the named Duff & Phelps Corp. joint administrators. "Rangers Football Club will continue as the football club it has been for 140 years."

Miller promised a new era of fiscal discipline at the club to make sure it never again went through the "anguish" caused by the mismanagement of previous owners.

"From now on, Rangers will live within its means -- no excuses," he said in a separate statement.

Neither Miller nor the administrator indicated the exact size of his latest bid. Nor did they say if it was substantially greater than Miller's previously disclosed conditional proposal, involving an acquisition price of £11 million plus a further £10 million a year in additional investments for the following three years.

Miller had previously said his offer would be dependent on what regime of sanctions against the club would be imposed by the Scottish Football Association and Scottish Premier League. But the administrator said Miller was now in talks with the regulatory body, and the talks would continue throughout the exclusivity period to find clarity.

The club's fans were previously said to prefer a rival approach from Scotsman Paul Murray and his Blue Knights consortium. But Murray was never in a position to offer an unconditional bid.

Crucially, Clark said Miller's bid would keep the Glasgow club out of liquidation and closure. It was strong enough to support a form of company voluntary administration, which would provide some return to the club's creditors.

Clark said it would not be possible for the club to enter a so-called standalone CVA, which would allow it to solve its problems without changing ownership. Such a deal would take too long and be too expensive, and the club would not survive.

Instead, Miller's proposal involved the use of a specially created "newco" in addition to the retention of the publicly listed Rangers Football Club. Clark said the business and assets Miller proposed to purchase would be sheltered in the new vehicle and returned to the public company once its finances had been cleaned up.

"[Miller] sees this route as a necessity rather than a choice, and in our view this is an entirely workable strategy," the administrator said, adding that the American's bid was substantially greater than anything else proposed and provided the best return to creditors. "Indeed, to ensure the continuing operation of the Club beyond the end of May, it is in our view a very compelling strategy."

Miller said it was an honor and a privilege to have the opportunity to buy what he described as "one of the world's great sporting institutions and one of the U.K.'s most venerable football clubs."

And he vowed there would be no repeat of the financial shenanigans of the past few years, which have pushed the club to the brink of liquidation and have left it owing money to creditors and with a tax bill running into millions of pounds.

The most recent owner, Craig Whyte, was recently fined £200,000 by the Scottish Football Association and banned for life from involvement in Association Football in Scotland.

"What Rangers, which includes supporters, players, staff and anyone with the club at heart, have been put through, particularly in recent months, is a travesty and from what I can see they have been badly let down by a number of individuals," Miller concluded.

"This will not happen on my watch should I become the custodian of this great club."