I don't think it's half. A lot of his "support" is astro-turfed and msm-projection, but his total amount of support is still a significant number. Probably somewhere north of 30% in my estimation. Very significant, but not a plurality.
Conversely, I believe the msm and IC has been working overtime to downplay the full extent of President Trump's support. Yesterday's Rasmussen presidential approval poll at 50% was very impressive, however for quite some time they have concealed their polling methodology at Rasmussen. Back before the pollsters comprehended that we had figured out their skewed polling system, they would publish their methodology in fine print at the end of their polling documents. Without exception they were left-leaning, often to the tune of 10% to 20% in favor of D's, this despite the fact there are about the same number of R's and D's registered in this country. This tells me they most of their polling in D-heavy areas. I believe POTUS Trumps actually support level is between 60% and 70% at this time.