Almost two-thirds of white Britons think immigration has been bad for the UK, according to a survey which anti-racism campaigners called a "disturbing picture" of society's attitudes.
Research commissioned by the Searchlight Educational Trust also found that Asians were most likely to back a halt to all immigration, at least until the economy had recovered.
Labour MP Jon Cruddas said the findings should "ricochet through the body politic" as they showed the potential for the rise of the far-right unless mainstream parties acted soon.
The poll, carried out by Populus, was one of the largest studies carried out on the subject, based on 91 questions to more than 5,000 individuals.
Immigration was held to have been on the whole a bad thing for Britain by 63% of whites, 43% of Asians and 17% of black Britons.
It found that 39% of Asians, 34% of whites and 21% of blacks believed immigration should be halted either permanently or at least until the UK's economy was back on track.
Almost half (48%) were open to supporting a new far-right party as long as it eschewed "fascist imagery" and did not condone violence. And 52% agreed that "Muslims create problems in the UK".
Ethnic minority communities generally feel less "proud" at seeing the English flag flown - though only 25% of whites questioned said they felt that emotion.
The Trust said the report, titled Fear And Hope - The New Politics Of Identity, "paints a disturbing picture of our attitudes towards each another and the unknown".
"It also graphically highlights the dangers that lie ahead if the issues highlighted in the research are not addressed.
"Fear And Hope throws down a challenge to the political parties to really understand what is happening in the body politic and then do something about it."
Director Nick Lowles pointed to some positive findings: "Young people are more hopeful about the future and more open to living in an ethnically diverse society.
"The vast majority of people reject political violence and view white anti-Muslim extremists as bad as Muslim extremists and there is overwhelming support for a positive campaign against extremism."
But he added: "This report gives those of us who are campaigning against extremism nowhere to hide. The harsh truth is we are in danger of losing touch with the public on race, immigration and multiculturalism.
"The attitude of all sections of the community to these complex issues is now running far ahead of the politicians and community leaders."
In the foreword to the report, Mr Cruddas wrote: "Put simply, unless political parties step up and provide a new language of material well-being, of identity and belonging, then these political forces might refract into more malign forms. As such, the political class has been warned."