A British equivalent of Barack Obama would find it extremely difficult to become prime minister, the head of the UK equality watchdog has said.
Trevor Phillips, chairman of the Equality and Human Rights Commission, told the Times the problem would not be voters but the political "machine".
He claimed even someone of Mr Obama's talent would struggle because the system was biased against change.
He said it was harder to reach the top for those who "did not fit the mould".
Mr Phillips told the Times: "If Barack Obama had lived here I would be very surprised if even somebody as brilliant as him would have been able to break through the institutional stranglehold that there is on power within the Labour Party."
Labour said it had a "proud record of promoting ethnic minority candidates".
It has 13 MPs from these backgrounds while the Conservatives have two and the Lib Dems presently have none.
But Mr Philips described what he saw as "institutional resistance" to selecting black and Asian candidates.
Mr Phillips later told the BBC Radio 4 Today programme it would be very hard for people who were not the right gender, class or race to reach the very top because of the current political system in place.
He said: "That's exactly the point that has been made about systemic bias - it is exactly the point that this, that what is thought, what's called - it's not a phrase I use, by the way - institutional racism.
"But it's a point about the fact that systems can sometimes work in such a way that, in spite of everybody's goodwill, in spite of the fact that everybody wants it to change, it doesn't change."
The parties... are all very happy to sign up to the general idea of advancing the cause of minorities but in practice they would like somebody else to do the business
He also said he did not think the public "would be at all resistant to electing a black prime minister.
"In fact I think in this new age, following what's happened this week, they would rather like it," he added.
"My point is that it's very difficult for people who don't fit a certain mould - and that is to do with gender, it's to do with race and it's to do with class - to find their way into the outer reaches of politics."
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In the Times, Mr Phillips said it was no coincidence that there were only 15 ethnic minority MPs.
"The parties and unions and think tanks are all very happy to sign up to the general idea of advancing the cause of minorities but in practice they would like somebody else to do the business," he added.
But Under-Secretary of State for Communities and Local Government Sadiq Khan said Labour's system of choosing candidates and its party leader reflected minority representation.
He also said he believed the British electorate could elect a black prime minister.
He told the BBC: "I work with very talented, very able black politicians and I know from talking to constituents around the country, that our constituents are very sophisticated and we judge our politicians by their policies not by the colour of their skin."
'Giving an edge'
Mr Phillips said he believed the Conservatives had performed better than Labour in increasing the number of black and Asian parliamentary candidates.
"[The Conservatives] are less democratic. They are happier to impose candidates on the local parties."
Mr Phillips went on to say that he opposed all-black shortlists for parliamentary candidates because it would be difficult to define "black" or to decide where they should be imposed, but he said action was needed by all parties.
"Any positive action has to be based on giving people who are already competent a bit of an edge," he said.
Last month Mr Phillips warned more help was needed for areas where there was a "white underclass" which had been "neglected" by existing equalities policies.
And in 2004 he argued multiculturalism belonged to a different era and that all citizens should "assert a core of Britishness".
Responding to Mr Phillips' claims, Labour said it continually reviewed its procedures to ensure its elected positions reflected British society.
A spokesman added: "This is the party that produced, among others, the first black woman MP, the first black minister, the first black woman minister, the first black Cabinet minister, the first black woman Cabinet minister and the first black woman mayor."
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