Liberal Democrat leader Jo Swinson | Peter Summers/Getty Images Liberal Democrat leader stands by promise to cancel Brexit The party’s leader said it would be “a nonsense” for the UK’s most pro-EU party to negotiate a Brexit deal should they win power in the upcoming election.

LONDON — Britain's only political party pledging to cancel Brexit if it wins power on December 12 is "just being honest," its leader said.

Jo Swinson, whose Liberal Democrats have gone into reverse in the polls since the U.K.'s general election was called, admitted the opportunity for a "seismic change" in British politics, which many predicted earlier in the year, had "moved on for the immediate moment."

Activists have raised concerns about the party's controversial decision to pledge to halt the process of pulling Britain out of the European Union without a second referendum, a policy which many say has gone down badly with voters.

However, Swinson defended the decision.

Speaking to POLITICO's London Playbook, she said the party had debated and voted on the policy at its conference in September.

"It has the virtue of just being honest, we still support a People's Vote and still want to stop Brexit in any way that we can. The thought that we would go and negotiate Brexit as the most pro-European party is a nonsense, right?" she said.

It is a "pretty mainstream" position to want to remain in the EU, she added.

The future of the EU

Asked if Britain would ever join the euro — the official currency of 19 of the 28 EU member countries — if that were required should the U.K. ever want to rejoin the European Union after Brexit, Swinson said it would not be necessary.

"I don't think that that is the right currency for us," Swinson said. "From the discussions that I've had [with colleagues in Brussels] I don't think that would be required either," she added.

In a speech last year, the EU's chief Brexit negotiator Michel Barnier said that if the U.K. changed its mind about Brexit once it has left the EU, it would have to reapply for membership “like a third country."

EU leaders have always insisted that any country which joins the EU is expected to adopt the single currency, although the U.K. and Denmark have negotiated opt-outs.

Swinson also admitted she "did not know enough detail" to be able to say whether she would support Albania and North Macedonia's bids to join the European Union, a key debate among European leaders.

"I have to say I have not sat down and gone through the various pros and cons," she said.

"I think in general terms it can be helpful to encourage countries to raise their records on human rights by engaging in [accession] discussions, even if in some cases it might take quite a long time for that process, and that progress to be made," she said.

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