Boris Johnson is at loggerheads with chancellor Rishi Sunak over the prospect of a rail strike, according to reports today.
Unions yesterday voted for the first national strike on the railways for decades with 89% of RMT members in favour of a walkout.
RMT leaders will now decide where to target action that could see huge swathes of the network closed after 7pm this summer.
Industry executives are said to be keen to offer the rail unions a pay rise of around 5% but the Treasury is concerned making rail a special example would spark a furious response from other public sector workers.
Johnson apparently wants to compromise and settle with the unions but Sunak is digging in his heels and refusing to lift the 2% public sector pay cap despite UK inflation hitting 9%.
Relations between Johnson and Sunak are already said to be fraught due to their differing stance on a windfall tax, with the situation coming to a head yesterday with Ofgem saying it would raise the energy price cap by a further £800 in October.
That would take the average fuel bill for a UK household to around £2,800 and push around 40% of the population into fuel poverty according to several energy suppliers.
Sunak has already introduced a £200 loan scheme plus an additional £150 to the most vulnerable to help alleviate the last rise in the energy cap to £1,971, but suppliers suggest that is nowhere near enough.
A new set of help measures is expected to be unveiled tomorrow and partly paid for by a windfall tax.
Options on the table are said to be an increase in the Warm Home Discount Scheme to £500, a direct government-funded reduction in fuel bills or a temporary VAT reduction.
Leaks at the weekend suggested that a windfall tax will be expanded to include power generators such as SSE and Drax in addition to oil majors such as Shell and BP.
Independent think-tank the Resolution Foundation said to have any impact the value of the new measures would have to be well in excess of £10bn.
Government sources said it was possible the new measures would be unveiled on Thursday but if Johnson and Sunak cannot resolve their differences there might be a delay until parliament returns early next month.