Returning the East Coast Main line to the private sector will “revitalise” it, ministers have said as they kick-started the franchising process.
The line has been publicly run since 2009 when National Express handed back the franchise amid financial problems.
Ministers say the line has since been “stabilised” but they now want to “rekindle the spirit of competition”.
Labour and the unions say the move is “ideological” and the line should remain in public ownership.
They say the failure of two successive operators to make the line – which runs from London to Edinburgh, with connected services to Inverness and Aberdeen – commercially viable and its improved performance in recent years show it can succeed under public ownership.