If, say, 5% of Republican voters decide to stay home because Trump is the nominee, we end up the same place that Romney left us -- because 5% of the Republican voters stayed home because either a.) Romney wasn't conservative enough or b.) he was a Mormon.
In 2016, the 5% could range from a.) conservatives who recognize that Trump isn't really a conservative to b.) RINOs who are appalled at Trump's often unconventional behavior.
Consequently, I should think that Trump becomes a problematic nominee -- he risks losing the election by losing a potentially decisive segment of the Republican vote.
Supporters of his nomination must, therefore, be prepared to take this risk -- while hoping that Trump will draw enough support from previous non-voters and some Democrats to compensate.
Maybe he will...maybe he won't.
Trump will likely have a lot of people who don’t normally vote republican voting for him which is something Romney did not have. Romney was not a candidate that got people excited and Trump arguably is. I don’t see Hillary as being very exciting for democrats or getting as many people out to vote for her as Obama did.
“Supporters of his nomination must, therefore, be prepared to take this risk — while hoping that Trump will draw enough support from previous non-voters and some Democrats to compensate.”
No problem, he’s already got black people and independents who are excited to vote for him.
As well as many Republicans who stayed home for McAmnesty and Romney. Trump’s policy papers, which are much more conservative than any other candidate in the field, especially the one on illegal immigration, will bring out fed up Republicans, Democrats, and Independents in droves.