After spending weeks fulminating against the evils of illegal immigration, the Republican aspirant has revealed he employed an undocumented nanny for five years at his dollars 4m mansion in Santa Barbara, California, in breach of US federal law.
This confession, wrung from him after the press began investigating his household staff, must have been very painful, not least because the hypocrisy of Washington politicians is one of Mr Huffington's favourite themes - a charge he regularly hurls at his Democratic opponent, Dianne Feinstein, the former mayor of San Francisco.
It is doubly awkward because last week Mr Huffington declared his support for Proposition 187 - a bitterly-disputed proposal to stop California's 1.6 million undocumented immigrants receiving health care, welfare, and education.
The affair is yet another setback to Mr Huffington's high-spending bid for power. Although he has risen from obscurity to being within several poll points of Ms Feinstein, he has been dogged by suggestions that he is the puppet of his wife, Arianna Stassinopoulos, an author and international socialite.
Particular attention has focused on Mrs Huffington's links with a New Age church led by a former school teacher who awoke from a coma three decades ago convinced that he was a deity.
Opponents will emphasise that Mr Huffington, a 'law and order' man, should have been aware of the immigration law as he was a congressman during the 'Nannygate' scandal over nominees for attorney general, in which Zoe Baird and Judge Kimba Wood withdrew their names after admitting hiring illegal immigrants.
Mr Huffington may also be obliged to reflect upon a recent speech: 'We have cut corners, looked the other way and sent the wrong message - that breaking the law pays, that only fools go through the proper immigration channels.
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