Mitt Romney, whose campaign is preparing a multi-million dollar wave of negative advertising to persuade voters that Rick Santorum should not be president, says he is open to the possibility of choosing Santorum to be his running mate should Romney win the Republican nomination. Romney appeared on Fox News Wednesday morning and was asked, "You and Rick Santorum, we haven't seen you go head-to-head yet…In the big picture, could you see a scenario where you two team up?" "Oh, I think it's always possible to have people come together in our party, whether it's Rick and I, or others in...