Talks aimed at averting train strikes before Christmas are expected to continue on Monday after the RMT union rejected an initial offer by the group representing train companies.
The latest round of strikes by union members at 14 train firms and Network Rail is due to begin in eight days.
The Rail Delivery Group (RDG) said its offer would allow for a 4% pay rise this year and another 4% next year.
But the RMT said the offer did not meet its criteria for pay or conditions.
Industrial action is currently due to take place across four 48-hour periods: 13-14 December, 16-17 December, 3-4 January, and 6-7 January.
Industry sources have said that if the strikes are to be called off, this needs to happen by the end of Monday to avoid disruption for passengers.
The RDG – which represents the 14 train operators – set out a number of proposed changes to working practices which it said would help to fund a pay rise for staff of 4% this year, backdated to the beginning of the financial year, followed by another 4% next year.
These include repurposing or closing ticket offices, with staff having new “multi-skilled” roles and Sunday working where it is not in place already.