Labour calls for West Coast Mainline franchise review
Labour is urging ministers to delay signing a new West Coast Mainline contract until Parliament returns.
The party says MPs must have the chance to consider the decision to take the franchise from Virgin Trains and give it to FirstGroup for the next 13 years.
FirstGroup says it will bring in key improvements for passengers but critics fear it will not be able to afford the £5.5bn it is paying for the franchise.
The Department for Transport said it had "no reason" to delay the signing.
That is due to happen as early as Wednesday with a "cooling off period" due to end at midnight on Tuesday.
But Virgin's Sir Richard Branson has offered to run the service "for free" while a review is carried out.
The Department for Transport spokesman said: "We note the offer that one of the bidders appears to have made via the press.
"However, the winning bidder was decided by a fair and established process and no reason has been advanced to convince DfT not to sign the agreement."
Aberdeen-based FirstGroup already operates a number of rail routes including Great Western and ScotRail.
The company, under the name First West Coast Limited, will take over the franchise from 9 December and is due to to operate the service until 2026.
The West Coast Mainline route serves 31 million passengers travelling between London, the West Midlands, the North West, North Wales and the central belt of Scotland.
Virgin has run the franchise since 1997, during which time passenger numbers have doubled.
FirstGroup has promised to introduce better wi-fi and food, more frequent trains and more seats, and to cut standard fares by 15%.
The firm said it would introduce 11 new 125mph six-car electric trains on the Birmingham to Glasgow route and provide more direct services between destinations.
Tim O'Toole, FirstGroup chief executive, said it had won the bid for the West Coast Mainline franchise "fair and square".
He added: "We are pleased that the Department for Transport sees no reason to revisit the process.
"We can understand why Virgin are disappointed to have lost, but the fact is that under its stewardship, the West Coast Mainline has experienced the poorest punctuality and reliability of any route in the country whilst our franchises are all above 90%.
"Virgin has also had a higher level of passenger complaints than all four First franchises put together. Our job over the next 14 years will be to put that right and give passengers a railway that is good value, reliable and offers great service."
But BBC deputy political editor James Landale said there was a fierce lobbying campaign, in the final hours before pen is put to paper, to put the decision on hold.
More than 100,000 people have signed an online petition calling for the decision to be reconsidered.
Labour's Maria Eagle, the shadow transport secretary, is urging the government to put the contract on hold until MPs return and have a chance to consider the deal.
And Labour's Louise Ellman, who chairs the House of Commons transport committee, has written to Transport Secretary Justine Greening asking her to delay signing the contract.
On Sunday, Sir Richard said that if reviewing the decision meant the December deadline had to be postponed, his company and Stagecoach would be willing to continue operating the railway lines while donating any profits to charity.
Speaking on Monday, Sir Richard told the BBC that he wanted a proper examination of the facts.
"We've asked 40 questions - not one of them have been answered. What we want is transparency.
"If the figures stack up, we'll bow out gracefully, we'll be very happy, we've got lots of other things to do, we'll move on in a month's time.
"But what should not happen is, tomorrow, the Department for Transport shouldn't rush through, get this signed and keep all these facts under cover."
Bruce Williamson, from the pressure group Railfuture, said Louise Ellman's call for a pause before the contract is signed was "significant".
He added: "The online petition, last time I looked, it was up to 133,000 signatures, which means that it triggers a parliamentary debate. So it would be a little bit bizarre to have a parliamentary debate in the next couple of weeks, sort of after the horse has bolted."