First Minister urged to back second EU referendum

The Lib Dems have been calling for the nationalists to join their campaign for a second referendum once the terms of the UK's departure from the EU are known.

Nicola Sturgeon has said a second vote could become ''irresistible'', but has stopped short of backing one.

Sir Vince is expected to urge her party to ''choose the national interest over party interest'' when he addresses delegates in Aviemore on Saturday.

He will say: ''Our campaign for a people's vote on the final deal is building in strength every week.

And I am pleased to see people from across the political spectrum getting behind it.

But a notable absence is the SNP. My party is working with the SNP to keep the UK in the single market.

But it is not enough for the SNP to lament the consequences of Brexit, and of leaving the single market.

In today's political environment, Brexit is not - or doesn't need to be - inevitable but time is running out for the SNP to play their part in stopping it.''

He will add: ''We are now winning big votes in the House of Lords on the EU Withdrawal Bill. One of the great ironies of our time is that it is a fundamentally undemocratic chamber which is being left to do the hard work of safeguarding democracy.''

Sir Vince will say that SNP votes in the House of Commons would be ''crucial'' if the Brexit legislation returns from the Lords with an amendment to enable a referendum on a final deal.

''So Nicola Sturgeon and the SNP will have a decision to make,'' he will say.

''The national interest or her party interest. Save the United Kingdom from Brexit, or pursue her dogged agenda of seeing Scotland out of both the unions which safeguard its prosperity.

Scotland surely will not forgive her if she makes the wrong choice.''