Transport Secretary Chris Grayling must "get a grip" on rail disruption which is "becoming a scandal", a former cabinet minister says.
Ex-defence secretary Sir Michael Fallon said he would leave his former cabinet colleague "in absolutely no doubt" of the "raw anger" of commuters.
Mr Grayling will face MPs' questions in the Commons later about the problems.
Despite hundreds of trains being removed from service, delays and cancellations have continued.
The problems stem from new timetables introduced last month.
Northern Rail has since brought in a new temporary timetable that removes 165 services a day, but on Monday more than 100 trains were still cancelled or severely delayed, affecting passengers in Manchester, Lancashire and the Lake District.
Govia Thameslink Railway, which runs Thameslink, Southern and Great Northern have also introduced a reduced service.
Mr Grayling has said the disruption was "wholly unacceptable" and has blamed Network Rail, which manages the system's infrastructure, for finalising the timetable changes too late.
But Labour has said the secretary of state - who has been meeting MPs from constituencies affected by the disruption - should resign.
One of the MPs meeting him, Sir Michael, who represents Sevenoaks in Kent, told the BBC: "This is becoming a scandal."
He said his constituents were unable to get to work or travel to school.
"It really is time now that ministers got a grip on this and force Thameslink to get on and run a decent service," he said.
If necessary drivers should be borrowed from other companies, he said, calling for the option of stripping the company of its franchise to be considered.
Asked about Mr Grayling's role, he said: "He's got to find some solutions to this."
"Clearly the transport secretary has to demonstrate today that he has this situation on board and that he's ready to use all his powers to start putting this right...commuter patience is running very thin."