Megyn Kelly called him out on it last night:
Chait dissects the dodge:
All these evasions cleverly managed to imply something without quite stating it. Has the question been raised many times? Yes — Romney has just never been forced to answer it. Did he favor letting states impose national mandates? Yes – but that’s not all he favored. Has Romney said he opposes a national mandate many times? Of course – since 2009, anyway. But has Romney always opposed a national individual mandate? Absolutely not.
The Dish 