Being a woman is more of a barrier to becoming an MP than being black or Asian, according to a survey of the candidates being chosen to stand at the next election.
The study suggests a crucial "tipping point" has been reached in the number of non-white candidates that the political parties are choosing.
The conventional wisdom is that it would take 75 years for Parliament to reflect Britain's ethnic mix. There are 13 Labour and two Tory MPs who are black or Asian, but no Liberal Democrat MPs. That number would have to rise from 15 MPs to 60 out of 646 to be representative of the number of non-whites in the population.
The Labour-affiliated Fabian Society predicts that the number of non-white MPs could rise to 25 after the next election as the Labour and Conservative Party pick more ethnic minority candidates, meaning that fair representation will be achieved much more quickly than previously thought.
In contrast, the three main parties are only choosing female candidates in about one in four seats. In 16 contests open to men as well as women, Labour has chosen only one woman. There are 125 women MPs, including 94 for Labour, 17 for the Tories and nine for the Liberal Democrats.
Sunder Katwala, the Fabian general secretary, said: "We seem to be making more progress on race than achieving equal chances for women in politics. Gender is a much more stubborn penalty than race. The gender penalty, though reducing, is still in place."
Although one explanation could be that sexism is more deep-rooted than racism, he said a more plausible one is that the "gender penalty" may be caused less by direct discrimination or cultural stereotypes about who should be an MP and more by problems such as child care and financial sacrifices.
Mr Katwala added: "It is not so difficult for a political establishment to give up 7.5 per cent of its seats [to ethnic minority candidates]. This can be done by finding those black and Asian candidates who fit the mould – the Oxbridge graduates, lawyers and accountants. Giving up 50 per cent of the seats [to women] is more difficult and may demand more cultural change."
The Fabian Society concludes that there is no need for parties to choose candidates from all-black shortlists, an idea that pressure groups such as Operation Black Vote are pushing and that the Government is considering. All-women shortlists were instrumental in raising the number of women Labour MPs at the 1997 election.
Labour is selecting black or Asian candidates in about one in 10 seats, with a higher rate of 14 per cent in marginal constituencies. So far, the Tories and Liberal Democrats have chosen non-white candidates in about 5 per cent of seats.
Labour could have 16 or 17 black or Asian MPs after the election and the Tories seven or eight but the Liberal Democrats may still be without any, say the Fabians.
Claims that it would take 75 years to secure fair representation for non-whites are "out of date" and "not at all credible," according to the study.