Jo Swinson says she can win ‘hundreds of seats’. Are the Lib Dems being realistic? Beyond 100 seats, the Lib Dems start to hit rock-solid, 20,000 vote majorities – and Brexit support in their own heartland

The Liberal Democrats are within a “small swing” of winning “hundreds of seats”, Jo Swinson said on Wednesday as she made an audacious pitch to be Prime Minister on 13 December.

The extraordinarily bullish message from the Lib Dem leader follows a record number of high profile defections to her party over the past six months, taking her tally of MPs from 12 to 19.

But can the Lib Dems really hope to secure an outright majority from such a low base? Even the most loyal of Lib Dem figures would privately admit this is as likely as the Queen asking Father Christmas to form a government.

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What is possible is that Ms Swinson’s party can snatch seats from the two main parties in high remain voting areas. The Lib Dems have a clear anti-Brexit message – if they win power they will revoke Article 50 and cancel the UK’s withdrawal from the EU, but if that doesn’t happen they will continue to fight for a second referendum. A vote for the Lib Dems is clearly, unequivocally, against Brexit.

Tactical opportunities

As a result, they can hope to pick up a substantial amount of support from both Labour and Tory pro-remain voters, particularly if there is a “remain alliance” where other parties agree to step aside in some seats, or if people are encouraged to vote tactically against Brexit.

This may get them close to winning 100 seats – but beyond that threshold there are rock-solid majorities of more than 20,000 in even the most remain-supporting of constituencies where voters would stick with the incumbent. What’s more, one of the Lib Dems’ previously strong regions, the south west, also has a pro-Brexit tendency.

The Lib Dem leader told Radio 4’s Today programme: “This is a volatile time in politics. Nobody needs to look at received wisdom or what’s happened in the past. Our polling shows that we are within a small swing of winning hundreds of seats, because the political landscape is so totally changed by what has happened in our country post-Brexit.”

A loose alliance

Ms Swinson’s major role on 13 December may not be as Prime Minister but as kingmaker, given another hung parliament could be on the cards. However, she has repeatedly said that neither Boris Johnson nor Jeremy Corbyn is “fit to be Prime Minister”.

She could play a role in offering the support of her MPs in a looser arrangement than a formal coalition, or if she can put pressure on one of the larger parties to change their leader – although this would be unlikely.