In open primaries. the democrats have been picking the weakest republican candidate for decades. Notice that Trump never got close to 50%. The democrats know this in the open primary states.
There were up to 17 people in the race when it started. Getting 40% with 4 candidates is very good. You will also notice that Cruz, Kasich, Rubio, etc. got considerably less in most states. Trump has 7.8 million votes so far, Cruz has 5.7 million. That is a substantial difference. However badly you think Trump is doing, the indisputable fact is that Trump is doing considerably better than Cruz.
“Notice that Trump never got close to 50%. The democrats know this in the open primary states.”
Trump got almost 46% of the vote with 4 candidates running in Florida ... I believe Florida is a closed primary.