Shrewd analysis from William McGurn in the Wall Street Journal:
Mr. Trump's critics are quick to suggest these kind of things make him unfit for the Oval Office. Especially on the right, they frequently go on to add that any Republican or conservative who does not publicly pronounce him anathema will forever bear the mark of Cain.
It should be noted that his critics on the right are also invested in a big GOP defeat. If Mr. Trump loses by two or three points, they will be blamed for contributing to that defeat. If, by contrast, Mr. Trump loses by a landslide, they will look like prophets.
For the larger Republican Party, however, there's a catch. If it turns out Mr. Trump loses by a narrow margin, Republican senators and congressmen still have a chance of keeping their seats. A blowout defeat for Mr. Trump, on the other hand, would likely translate into massive Republican losses in both the Senate and House. Even so, it's a price the NeverTrump movement appears more than willing to pay to make their point.