The new team running trains in the north of England has been given 100 days to produce an improvement plan.
Transport Secretary Grant Shapps said he hoped the new management would make a “significant” change now the franchise had changed hands.
But he also warned that it would take time for the changes to take effect.
Robert Gisby, the new chair of Northern trains, promised passengers cleaner trains with improved capacity and timetables.
The new government-owned Operator of Last Resort (OLR) took over on Sunday from Arriva Rail North, which ran a service in which passengers experienced regular delays and cancellations since a timetable change in May 2018.
Mr Shapps said: “I am asking the new leadership to give me a plan in 100 days of all the things that will make a significant change.”
He added: “We will make some obvious changes immediately. Trains will be deep-cleaned, with Sunday services re-running.
Analysis – Judy Hobson, transport correspondent, BBC North West Tonight
What Grant Shapps is really talking about is timetable change.
And this probably means passengers can expect longer trains but fewer of them.
Robin Gisby says he is going to be asking the Government for more money.
The question long-suffering passengers are asking is – will he get it?
“But it will take time and it is important that people know it is actually the same trains and same teams – things won’t change overnight.”
Mr Gisby said: “We’re going to look at capacity, particularly in and around Manchester – there are some things we need to do on the timetable there.”
He added: “We need to look at the state of the trains – they need to be cleaner.”
OLR already manages the London North Eastern Railway (LNER) franchise after railway services on the East Coast Main Line were brought back under government control in May 2018.
Northern services have transferred from Arriva Rail North to Northern Trains Limited – a newly-formed subsidiary of OLR.