This is where there is a difference between the establishment and the conservative movement. The establishment might be willing to cut their losses, lose in 2016, but keep Congress, and win in 2020. But, both that and the mere idea of Trump being the GOP nominee is unacceptable to the conservative movement.
Trump winning may be unacceptable to the conservative movement, but that shows that perhaps the conservative movement isn't popular enough
within the GOP to be able to win the White House, let alone a general electorate.
If the conservative movement was truly as thriving and popular as it says it is, Ted Cruz would be past the magic 1237 right now.
