Rail operator Govia Thameslink faces being stripped of its franchises unless performance on its services in the South East of England rapidly improves, the BBC understands.
A source said the government could begin the process within weeks.
Passengers on its Thameslink and Great Northern trains have endured more than a month of disruption following the introduction of new timetables in May.
Meanwhile, the firm said it is working on plans to compensate passengers.
"The industry is working together on this and an announcement will be made in due course," said a spokesman for Govia Thameslink Railway (GTR).
The BBC understands that commuters are set to receive compensation worth a month's travel.
GTR - which also runs Southern and the Gatwick Express services - changed the time of every train on its timetable on 20 May.
Passengers were warned of disruption before the changes were brought in, but the implementation of the new timetable saw some services withdrawn and further cancellations without any warning.
Since then, GTR chief executive Charles Horton has resigned and Transport Secretary Chris Grayling has faced calls to stand down - as MPs from across all parties voiced their concern at the disruption caused in their constituencies.
'Last chance saloon'
Passengers have expressed their anger on social media, while last week a memo leaked by the RMT union revealed that extra security staff were at stations to protect staff from "unhappy customers".
But there is also frustration within government that while Northern, which encountered similar problems in the North of England, has introduced an interim timetable, Govia Thameslink's equivalent is still a fortnight away.
"They are now in the last chance saloon," a government source told the BBC.
What do passengers say?
Will Graves, from Arlesey in Bedfordshire, spends around £400 each month commuting to London - but told the BBC the current service is "the worst I can remember in my 14 years of commuting".
Mr Graves said that trains are regularly cancelled and almost always delayed - often due to no driver being available.
"When you do get on a train, you're standing shoulder to shoulder - it's horrendous," said Mr Graves. "I think I've had only one journey that hasn't been delayed in the last month."
Trent Gashi, who commutes from Flitwick, Befordshire, to London, described Govia Thameslink's service as an "utter farce" and said ticket price rises in 2018 had "added insult to injury".
"Trains are cancelled without notice, people are ferried on and off as if they are livestock," said Mr Gashi.
"They make so much money out of people like us. It needs to be seriously addressed by the government."
Mick Cash, general secretary of the National Union of Rail, Maritime and Transport Workers, has called for the UK's privatised rail networks to be brought back into public ownership "on a permanent basis".
He described the "last chance saloon" comment as "empty rhetoric" that tells "these basket-case companies" that they have been "let off the hook again while services are reduced to chaos".
'Months of chaos'
He added: "This is no time for empty threats from unnamed government sources."
Mayor of London Sadiq Khan said that, after "months of chaos" for passengers, he was in favour of Govia Thameslink losing its franchise.
He tweeted: "City Hall will push for @TfL to take over more commuter routes so we can provide Londoners with a better service."
A spokesman for Govia Thameslink refused to comment on the reports about the possible loss of the franchises, instead choosing to re-release a statement in which it said it was "sorry for the disruption".
GTR had added it rescheduled every train in its franchise in an attempt to improve rail efficiency but it was a "hugely complicated task" and involved re-training drivers on new routes.
Mr Grayling had previously announced there would be compensation for commuters and an inquiry into what went wrong, saying there had been "major failures" by the rail industry.
A Department for Transport spokesman added: "GTR passengers are encountering unacceptable service levels and the transport secretary and rail minister have been clear it is their priority that this is put right as soon as possible."