Well that was a surprise, wasn't it? Romney claims he will provide 12 million new jobs. But that's the consensus view of economists for the next four years regardless who is president. So Kessler goes through the specific Romney campaign claims for job growth and what studies lie behind them:

The specifics — 7 million plus 3 million plus 2 million [jobs] — mentioned by Romney in the ad are not in the white paper. So where did that come from? We asked the Romney campaign, and the answer turns out to be: totally different studies … with completely different timelines…  For instance, the 3-million-jobs claim for Romney’s energy policies appears largely based on a Citigroup Global Markets study that did not even evaluate Romney’s policies. Instead, the report predicted 2.7 million to 3.6 million jobs would be created over the next eight years, largely because of trends and policies already adopted — including tougher fuel efficiency standards that Romney has criticized and suggested he would reverse.

He's a massive, practised, knowing liar.