captions by vitac www.vitac.com under two hours from the start of iowa s presidential caucuses. a vote to shrink the field and perhaps give us a front-runner. mitt romney predicting, quote, we re going win this but his opponents are promising the governor will have a much harder time after tonight. this afternoon the former house speaker newt gingrich told reporters his ads will start drawing, quote, a sharper, clearer contrast with governor romney and on cbs this morning, the former speaker, remember, he s the candidate who keeps promising to stay positive, well, gingrich called romney a liar. are you calling mitt romney a liar? yes. why are you saying he s a lier? this is a man whose staff created the pac, his millionaire friends fund the pac. he pretens he has nothing to do with the pac. it s balogna, he s not telling the american people the truth. it s like a pretense he s a conservative. governor romney s laughing off gingrich s attempt to be more aggress