A Tory rebellion against a crucial High Speed 2 rail project bill is not expected to be enough to stop it from going through in the House of Commons later today.
When the legislation was last in the Commons, 21 Conservative backbenchers voted in favour of an amendment to quash the project.
If the rebels wish to defeat the bill tonight they will need to win significantly more support from all parties.
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Accompanied by the Duke of Edinburgh, the Queen will attend the opening ceremony of the fifth session in the Holyrood chamber.
Ms Leadsom has received the backing of Ian Duncan Smith, the former work and pensions secretary.
The former shadow work and pensions secretary is considered a more viable candidate than Angela Eagle, a Labour source has told ITV News.