Conservative MPs have backed temporary nationalisation of the failing rail franchise that includes Southern Railway amid reports the Government is poised to step in.
Ministers are preparing a number of options, ranging from splitting off Southern from Govia Thameslink Railway, to a complete "managed exit" to take direct control of the entire franchise until a new contract could be let, it has been claimed.
The plan has its own codename and a potential interim managing director has been identified, according to the Rail Business Intelligence magazine.
Downing Street said there were "no plans" for renationalisation but rail companies were aware of the "consequences" if they failed to perform.
Tory former minister Tim Loughton said he was glad Transport Secretary Chris Grayling "is not ruling anything in or anything out".
The East Worthing and Shoreham MP added: "Constituents are so desperate that we really do need to get this situation resolved.
"If that involves temporarily bringing it into government control while the situation is sorted out, so be it."
Croydon South Tory MP Chris Philp said he backed taking the service into temporary public control.
"It is an abysmal service that has inflicted misery on constituents," he said.
"The franchise is far too big but the unions have made a bad situation far worse."
But Crispin Blunt, Conservative MP for Reigate, said putting the service into government hands was unlikely to improve the situation.
He said: "It's difficult to see how it would improve matters except, perhaps, by making customers feel happier for a day or two that GTR would appear to have been punished."
Mr Blunt said the terms of the franchise and the London Bridge upgrade meant GTR was making "limited profit at huge damage to their corporate brand" and the company would probably have given up the contract if it did not face huge penalties.
The MP said there were no decent alternative options and said the franchise "shouldn't be lightly tossed away".
But he called for the Treasury to "get serious" about providing funding to ensure there are "proper compensation options" so passengers only pay for the service they receive.
He said: "If there were any decent options, they would have been taken by now."
Aslef and Southern have been involved in lengthy talks to try to resolve a row over driver only trains, one of the disputes which has affected services for several months, as well as staff shortages and other problems.
Discussions started a week ago, but neither side has commented on whether any progress is being made.
A small number of members of the Rail, Maritime and Transport union at Southern went on strike on Wednesday and will walk out again on Friday.
A Number 10 spokesman said: "Broadly we have been very clear that we expect to see improvements from the operator of Southern, the service isn't as good as it should be.
"But there are no plans to strip Govia Thameslink Railway of the Southern franchise, it is purely speculative reporting."
Asked if the Prime Minister had sympathy with Tory MPs supporting renationalisation, the spokesman said: "We have been very clear the performance of Southern isn't good enough and we expect there to be improvements. We are working with Southern and Network Rail to bring about those improvements.
"The requirement is on the company to give its customers a much better service than it is now."
Asked how bad things would have to get before the company was stripped of its franchise, the spokesman said: "These things are kept under constant review. Those companies that don't perform to expectations will face the consequences in terms of potential penalties."