The Transport Secretary is seeking legal advice after a Virgin court challenge over the West Coast Main Line rail franchise.
Justine Greening told Channel 4 News she would be making her "next steps known" after consulting with lawyers on Virgin's 11th-hour application to the High Court for a judicial review into the decision.
But Greening expressed confidence in her department's decision-making process, adding that contingency plans were in place in the event of any delay.
Earlier this month, the government announced that Virgin Trains had lost out to FirstGroup in the bidding war to run a new 13-year West Coast Main Line franchise from December.
Sir Richard Branson reacted angrily to the decision, branding the bidding process "insane" and threatening to end all involvement with the railways.
Virgin Trains said it was starting court proceedings as it believed the procurement process had "ignored the substantial risks to taxpayers and customers of delivering FirstGroup's bid over the [13 years and four months] course of the franchise".
Virgin now hopes that its legal challenge will delay the imminent final signing of the franchise contract by Greening.
The BBC said she was entitled to sign it from midnight tonight following a cooling-off period.
Asked if the new rail contract could be delayed by Virgin's legal bid, Greening told Channel 4 News: "I believe that that may well be what Virgin are going to seek to do, but we will defend the robustness of the process as a department too."
But she acknowledged she would now need to seek legal advice before signing the new contract, stating: "Well, obviously I've got to now consult with lawyers and we will make our next steps known once we've had a chance to reflect on the papers that Virgin have now lodged with the court."
Commenting on the possible impact on the timing of the franchise handover, she said: "We have to look at all of that, but there are contingencies and plans in case there is any sort of delay that does involve a delayed handover."