Speaking alongside Guy Verhofstadt (center) at a campaign rally in north London, Lib Dem leader Vincent Cable (left) said his party was going into the European election with "momentum" | Tolga Akmen/AFP/Getty Images Verhofstadt backs Lib Dems on the ‘Bollocks to Brexit’ tour Vince Cable’s Lib Dems are the ‘natural’ home for Remainers, says ALDE leader.

LONDON — Remain-backing voters in the U.K. should vote for the Liberal Democrats as “the most pro-European” party, Guy Verhofstadt said on a campaign visit to London.

The Lib Dems face a challenge in the European election from new party Change UK and the Greens, which both share their policy of demanding a second referendum on EU membership.

But Verhofstadt, leader of the Alliance of Liberals and Democrats for Europe (ALDE), said that Vince Cable’s Lib Dems are the “natural” home for Remainers.

“If there is one pro-European party in Britain, it [is] the Lib Dems,” he said. “That has always been the case.”

Speaking alongside Verhofstadt at a campaign rally in north London, Lib Dem leader Cable said his party is going into the European election with “momentum” following positive local election results last week, which saw them gain more than 700 council seats across England.

Referring to the party’s new “Bollocks to Brexit” election slogan, he added: “We have a very clear, simple, unambiguous, honest slogan, which is ‘Stop Brexit.’ There’s a slightly cruder version … which you may have seen.”

Lib Dem MEPs, he said, would contribute to a “powerful liberal force in Europe to stand up to the ugly populism that is now happening in Britain and the rest of Europe.”

Asked about reports that the U.K.’s lead Brexit official, Olly Robbins, had asked him about becoming a Belgian citizen, Verhofstadt replied: “It was a joke … where is your British sense of humor? I hope in Brexit that you don’t lose that.”