The withdrawal of Mr Giuliani, once a front-runner himself, leaves the veteran Arizona senator facing a strong challenge from Mormon candidate Mitt Romney.

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Blade Runner is at once a classic film noir film and a masterful piece of science fiction.

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The Democratic front-runner, Hillary Clinton, once a creature of the left, has tried to remake herself as a centrist (she did strikingly well among conservative New Yorkers when she was re-elected to the Senate in November).

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If he, or Hillary Clinton, the Democratic front-runner, get the job, America may well once more take a lead in the global effort to mitigate climate change.

ECONOMIST: Climate change