Rail minister Chris Heaton-Harris has written to Train Operating Company (TOC) bosses to tell them there is "no budget" for any further subsidies to increase workers' pay.
TOCs are private companies and can set their own pay policy, but this is as close to an imposition of a pay freeze on railway workers as the government is capable of. TOCs will undoubtedly jump at the chance to tell workers their hands are tied, and there's simply no money available.
Heaton-Harris's letter says current subsidy levels are "not sustainable". A statement from the government's Rail Delivery Group said: "It would be unfair to increase the burden on taxpayers by funding rail industry pay rises, and we would only consider increases in exceptional circumstances."
The situation on Merseyrail, where RMT is balloting is members over the company's failure to even table a pay offer, is likely to be a sign of things to come.
No TOC will defy the government on this matter of its own volition; if the pay freeze is to be broken, it will be because workers' action forces concessions. Rail unions must meet as a matter of urgency and seek to agree a coordinated strategy.