Levin concludes that Romney is the better manager and sees the presidency as an executive position, which technically it is. That gives Romney the edge in Levin's view.
I see the presidency differently. Technically, the president is the CEO of the federal government. However, most cabinet departments operate pretty much by carrying out congressional mandates, with little input from the president. Foreign policy is the only sphere in which the president has substantial independence.
In reality, he (or she) is truly less the CEO than the nation's spokesperson. I ask myself which person I'd rather be looking at and listening to on the news for the next four years: boring, managerial Mitt or interesting, mercurial Newt. Newt wins this contest hands down, he is just more interesting.
Will I support whoever is nominated? If it is one of these two, yes certainly. Either would likely be a substantial improvement on the incumbent. Is it possible the Republicans could nominate someone I could not support? Of course.