A student described by Nigel Farage as "the future face of UKIP" and labelled its "ethnic minority poster girl" has quit the party, accusing it of racism.
Sanya-Jeet Thandi, a 21-year-old student at the London School of Economics, has accused UKIP of "descending into a form of racist populism".
Her resignation is an embarrassing blow for UKIP leader Mr Farage, coming just nine days before the Euro elections and less than a week after he staged a rally parading his party's black and Asian candidates.
At the rally, Mr Farage stood on the stage surrounded by ethnic minority candidates and claimed it was UKIP’s " Clause IV moment ", following allegations of racism and a spate of controversies involving party candidates.
He declared: "I don't care what you call us but from this moment on, please, do not ever call us a racist party. We are not a racist party."
But six days later, Ms Thandi hit out in an article for The Guardian.
"This anti-immigrant campaign undermines UKIP's claim not to be a racist party," she writes.
"They are turning the election into a game of 'us' and 'them'. Well, I am with 'them'.
"Yes, UKIP is a relatively young party. No, that is not an excuse to allow racists to stand for election. Nor is it an excuse to exploit the ignorance in British society and indulge the racist vote by telling them 'they’ll take your jobs'. Sorry, UKIP, you’ve lost another vote."
A UKIP spokesman said it was a "matter of sadness" when a member left the party, but said 500 a week were joining at present.
He said it was "ludicrous" to suggest that the party was heading in a racist direction, but that anyone was entitled to their opinion.
Several UKIP politicians have been criticised for racism in recent years, such as Godfrey Bloom who made a speech arguing that foreign aid should not be sent to "Bongo Bongo Land".
Last month, a UKIP candidate in the local elections said Lenny Henry should emigrate "to a black country" after the comedian called for more ethnic minority representation on TV.