A campaign is being launched to reverse the Government's controversial decision to scrap electrification of railway lines in Wales, the Midlands and the North.
Transport Secretary Chris Grayling sparked outrage with an announcement just before Parliament went into summer recess last month that routes between Cardiff and Swansea; Kettering, Nottingham and Sheffield; and Windermere and Oxenholme would not be electrified.
Manuel Cortes, general secretary of the Transport Salaried Staffs Association, is meeting Swansea West's Labour MP Geraint Davies to start a campaign which will spread to other affected areas.
He said: "Chris Grayling disgracefully cancelled the much-needed upgrading of the South Wales mainline between Cardiff and Swansea as Parliament was going into recess, so he couldn't be held to account in the House of Commons for his sneak U-turn.
"But there's more than one way to hold the Tories to account for breaking their promises.
"I will be meeting Geraint today to discuss kickstarting a new campaign in Wales which keeps the upgrading of rail across the country - not just in South Wales - at the top of the political agenda, and one which makes the Tories pay at the ballot box for the contempt they have shown to Wales.
"Labour's 2017 manifesto has already committed to bringing Welsh rail companies back into public ownership when the franchises expire.
"We will be now be working to ensure the next Labour manifesto pledges to reverse the Tories' broken promises and honour the commitment made to electrify Welsh rail lines as soon as the next Labour government gets into power."
A Department for Transport spokesman said: "We are investing around £40 billion in our railways as part of the biggest rail modernisation programme for over a century.
"We are delivering dual electric and diesel trains so passengers can benefit from modern services more quickly, without the need for disruptive engineering works."