Investor Warren Buffett, the world's second richest man, is to help Senator John Kerry's campaign to remove President Bush from the White House.
Buffett usually backs winners, at least in business
Mr Buffett, worth some $40bn, said he disagreed profoundly with Mr Bush's tax cuts for rich people like him.
"He (Bush) just has a different political philosophy than I do," Mr Buffett told the BBC.
Mr Buffett is pragmatic and endorses individuals and policies rather than parties.
"The sage of Omaha", as Mr Buffett is sometimes known, advised Arnold Schwarzenegger when he won in California as a Republican.
Not 'a good idea'
"In tax, policies have been tilted very much towards the rich, and I think that when the tax cuts took place they should have been far more for the middle class and people in poor economic status," Mr Buffett said.
Buffett's backing is welcome news for Kerry
"Instead, I got... more money in my pocket because of the tax change and I don't think it's a good idea," he added.
Mr Buffett is perhaps the most powerful business leader in the world.
His company Berkshire Hathaway owns swathes of corporate America from some of Coca-Cola to the country's biggest brickmaker.
Mr Buffett usually backs winners, at least in business, though that does not necessarily mean Senator Kerry will win in November's presidential poll.