It must be campaign rhetoric. If he really means it, chances are he is going to get booed out of his Hyde Park neighbourhood.
Less outsourcing would mean that American firms would face increased costs and decreased competitiveness, at a time when the economy isn't exactly going great guns. It would certainly lead to a backlash in India, with the result that US firms are going to miss out on the Indian growth story. Also, for every dollar that the US gives to an Indian software engineer salary it probably gets a good fraction of it back in the money that he/she eventually spends on Levis jeans and Coke and Dominos Pizza and iPhones. Why anyone would want to mess with that is beyond me, but you gotta do what you gotta do to get voted in.