republican candidates are back on the campaign trail this morning, defending their stances from tuesday night's debate. now, there's new focus on their differences and how they lead their party, and the country they're fighting to lead. ben carson was at liberty university yesterday warning students of secular progressives. >> the secular progressives don't care whether you agree with them or not, as long as you sit down and keep your mouth shut. >> meanwhile, ohio governor john kasich is continuing his theme from the debate. he's saying republicans need to be less extreme, and more pragmatic if they want to beat the democrats in 2016. but neither kasich nor carson can count on help from this man, charles koch. at least not yet. the billionaire industrialist told "usa today" he's unlikely to support anyone in the primaries. but is likely to help a republican in the general election. nbc's tracie potts is live in washington for us this morning, and tracie, donald trump once