Change UK leader MP Heidi Allen has challenged Brexit Party leader Nigel Farage to a live TV debate ahead of the European elections.
In her party’s election broadcast, Ms Allen said she thinks a debate is “overdue” as there is “so much at stake” in the vote on 23 May.
She said the leaders needed to “share with the British people our vision for the future”.
But Mr Farage has declined, saying: “Who is she?”
The challenge was made on Monday night at a Change UK rally in Cardiff.
Ms Allen – who left the Conservatives to join the recently-formed party – said she wanted to discuss in a debate the “open, global, outward Britain that I know that we are”.
“I’m challenging Nigel Farage to join me in a new live TV debate and let’s share with the British people our vision for the future and let them decide which they prefer,” she said.
At the scene: James Williams, BBC Wales
In a conference room at the home of Welsh rugby, Heidi Allen referenced the men in red’s 14-match unbeaten run and the Principality Stadium in Cardiff as the venue of many David and Goliath-style battles.
Change UK, she said, faces an equally big battle in achieving its main aim – a second EU referendum and the reversal of Brexit.
But, from my conversations with people after the speeches, many of the people in the 100-150 strong crowd are up for the fight.
They were a mixture of former Labour and Conservative voters who felt politically homeless because of Jeremy Corbyn and Theresa May’s Brexit stance.
“Politics is broken” was a common refrain from the Change UK MPs and candidates.
Few would argue. But how many believe Change UK is the party to fix it?
Anna Soubry, a former Conservative minister who left the Tories to join Change UK, told the BBC that Brexit presented a real predicament for both the Conservatives and Labour.
She said politics in this country was now “broken”.
“It is quite astonishing to think that the Labour Party is, in effect, prepared to facilitate Brexit,” Ms Soubry said, referring to the ongoing talks between the government and Labour.
“Labour is all over the place and it really is a disgraceful situation to see the party of opposition taking such an unprincipled and such a precarious and differing and argumentative stance within their own party.
“But the Tories are in the same predicament.”
But Labour MP Yvette Cooper has urged “all political parties to come together” to find a way through the Brexit impasse.
The UK had been due to leave the EU on 29 March, but the deadline was pushed back to 31 October after Parliament was unable to agree a way forward.
Who is standing in the European elections?
The UK is divided into 12 regions, each represented by between three and 10 MEPs depending on population size.
Seats in England, Scotland and Wales are awarded to parties according to their share of the vote, to candidates on lists drawn up by the parties.
Northern Ireland elects MEPs using a single transferable vote system, with voters able to rank candidates in order of preference.