More than half of Ukip supporters would be "uncomfortable" with a non-white prime minister in Downing Street, a new poll has revealed.
The findings will do little to dispel David Cameron's description of Ukip as a party of "closet racists".
According to figures by YouGov, 59% of Ukip supporters said they were uncomfortable with the thought of a PM who was from a British Minority Ethnic (BME) background.
A significant minority of followers of Nigel Farage's anti-EU party - 45% - said they were "very uncomfortable" with the idea.
Only 14% of supporters said they would be comfortable if the country was led by someone who was not white.
The findings for Birkbeck College and Demos came only weeks after Ukip MEP Godfrey Bloom caused uproar by describing countries overseas as 'Bongo Bongo Land.' He resigned the Ukip whip as he was about to be stripped of it by Farage, after calling female supporters "sluts".
According to the YouGov research, one in 10 Ukip supporters would also not feel comfortable having a non-white friend.
The research was angrily condemned by the party, which is hoping to make big gains at next year's local and European elections.
Gawain Towler, who is standing as an MEP for Ukip, said: "This is an agenda-driven poll which is designed to get the sort of results YouGov have doctored.
"It's time to stop this revolting obsession with racist accusations. The pitch of some of the questions asked I find distasteful. This sort of thing creates antagonism rather than addresses it."
Among the major parties, support for a non-white PM was far from strong across the political spectrum. Forty-one percent of Tory supporters said they were "uncomfortable" with a non-white PM, next to 28% of Labour supporters and a quarter of Liberal Democrat supporters.
Lib Dems were the most comfortable with the idea of a BME PM (47%), compared to Labour (43%) the Tories (33%) and Ukip (14%).
YouGov denied that the results had been doctored. A spokesman told IBTimes UK: "That is not the case at all. We've always been open about the results and we publish them in full on our website. This research is fully in line with what we do and we stand by the results."
Prof Eric Kaufmann of Birkbeck College commissioned the research. He said: "Differences between party supporters are not explained by divergent age, education, regional or class profiles.
"Young university-educated London Tories are significantly less comfortable with a minority prime minister than young university-educated London Liberal Democrats."
Kaufmann commissioned the survey as part of an in-depth study into white working-class people's attitude to diversity in Britain. YouGov surveyed 1,869 adults in July.