UKIP have been thrown into fresh crisis after Mark Reckless quit the Welsh wing of the party.
Reckless, a member of the Welsh Assembly, has defected back to the Conservatives but will not formally rejoin the party.
Instead, he will sit as a Conservative AM - making the Tory group the second-largest in the Welsh Senedd.
UKIP's Welsh Assembly leader Neil Hamilton, himself a former Tory, said Reckless had "betrayed the trust" of his colleagues and had "no mandate" to join the Conservative faction.
The news comes shortly after Douglas Carswell, UKIP's only MP, quit the party to stand as an independent and leave the eurosceptic party without a voice in Westminster.
UKIP enjoyed a spectacular triumph in last year's EU referendum but have been wracked by a series of crises since then, including the resignation of Diane James as leader after just 18 days in charge and a fight at the European Parliament which left her hotly-tipped successor Steven Woolfe in hospital.