FACTBOX - Suitors have less than two weeks to buy Rock

(Reuters) - The government has given suitors for Northern Rock NRK.L until February 4 to submit proposals for the ailing bank, after converting emergency funding to government-backed bonds to help smooth a deal.

Three proposals look most likely -- one led by Virgin Group, another by Olivant and a third from an in-house management team. Some private equity firms could re-enter the auction and, if all else fails, there is temporary nationalisation.

Here's a summary of the proposals:

VIRGIN

A consortium led by billionaire entrepreneur Sir Richard Branson is the front-runner though the government gets a stake.

Under a proposal unveiled in October, Virgin plans to inject 650 million pounds into the bank and take a 54 percent stake, and raise a similar amount from a rights issue. It would keep a stock market listing, fold in financial services firm Virgin Money and rebrand the bank under that name.

Its consortium also includes buyout firm WL Ross, investment group Toscafund and Hong Kong-based investment group First Eastern. It has links with U.S. insurer AIG (AIG.N).

Financial bookmaker Cantor Index rates the odds for Branson's team as 2/1.

OLIVANT

A consortium led by investment group Olivant and headed by veteran troubleshooter Luqman Arnold is favoured by many of Northern Rock's shareholders as it would retain the brand.

It promises a "simpler, smoother and quicker" offer that would keep the bank's name and listing but parachute in new executives, led by Arnold, the former boss of Abbey.

Under the plan about 650 million pounds would be raised through a rights issue. Olivant would take a 15 percent stake for about 150 million pounds and get warrants for more than 7 percent of the enlarged company. The government would be issued warrants for more than 5 percent of the shares.

Cantor rates Olivant's odds at 7/2.

IN-HOUSE MANAGEMENT

A rescue plan by an internal management team has gained in popularity over the past week.

A "self-help" or standalone solution could close the bank to new business so it runs off the mortgage book over several years to shrink its balance sheet.

Cantor gives it odds of 5/2.

JC FLOWERS, CERBERUS

U.S. buyout firms JC Flowers and Cerberus have not ruled out re-entering the auction, according to people familiar with the situation, after withdrawing from the process last month.

Cantor rates Flowers at 7/2 and Cerberus at 6/1.

NATIONALISATION

The government would run the bank and assume responsibility for its assets. However, comments last week increasing the threat of nationalisation may have been aimed at getting shareholders to support any private sector deal, and nationalisation is now only seen as a fallback option.

(Editing by Suzy Valentine)