Mitt Romney is the most impressive performer this evening, striking a judicious tone of urgency and fluency. His one remarkable statement was that he likes government mandates, and that they work. This is a startling deviation from his effort to position himself as the perfect conservative Republican. But as a matter of performance solely, he is far and away the best and he’s delivered it when he needed it most. UPDATE: John McCain, just after the halfway point, is hammering effectively at Mitt Romney for changing his tune on McCain’s own immigration plan and Romney is not doing as well with it.