Like it or not, Trump has beat all rivals for the Republican nomination before the convention has even started. Just about everyone, except perhaps Trump's supporters, is surprised that he is the nominee. If you are surprised, you probably do not understand his communications strategy. In an effort to determine why he is the presumptive nominee (technically he won't be nominated until the delegates cast their ballots), it is useful to analyze his communications strategy and why it has been effective to this point.
Talks like a teenager
After years of practice as a reality show host, the Donald has figured out how to use words that everyone will understand. This offends people that like to think of themselves as more intelligent and sophisticated, but it makes his message clear enough to everyone listening. Many did not like the slogan "squeeze the Charmin" but it sold a lot of toilet paper.
Repositions his opponents
He finds out the weaknesses of his opponents and exploits them. He also uses the Karl Rove strategy of taking the strengths of his opponents and turning them into weaknesses -- saying whatever he wants about them without much concern for the truth. This works with those that feel powerless and disaffected since they are looking for the hero that will save them from all the evils in the world.
His fans seem to like the fact that he attacks people of all parties and persuasions. In addition to his requisite attacks on Democrats, the Mexican Government, and Muslims, he has attacked conservative talk show hosts, such as Megyn Kelly, Republican war hero John McCain, Republican strategist Karl Rove, the Bushes, other Republican rivals, and even the Pope. Most politicians would suffer greatly for attacking any one of these. Not Trump.
Understands his target audience
Trump knows that a lot of people are unhappy with a lot of different things -- terrorism, illegal immigration, the economy post financial meltdown, security, changing demographics, political correctness, environmental regulations, and lots more. While it is easy to criticize those in positions of power, it is much more difficult to effectively change things for the better. A lot of those that feel powerless and disaffected want to believe that one guy, who has crafted an image as a very successful businessman, will come in and fix everything that they see as wrong.
Repeats enough times that those listening remember and believe
When a message is repeated enough times, many will believe it whether it is true or not. He has been using the term "crooked Hillary" quite a lot lately. After sufficient repetition of those words, a lot of people believe them. Never mind that Trump has been sued for fraud in his home state for Trump University and has been involved in at least 169 Federal lawsuits. According to Bloomberg, Trump has either sued or been sued, 1,300 times since 2,000.
Knows how to use the media for free
Trump knows that being outrageous will attract attention. Every time he appears, he attracts demonstrators, and he uses the demonstrators, in and outside the venue in which he is speaking, to further his "tough guy" no nonsense image. Of course, the media lives off of celebrities that attract attention. Trump lovers and haters alike are attracted to him because they are anxious to see what he is going to do next. The other Republicans running against him were frustrated and jealous of the attention he received. He proved this when he pulled out of the Fox news debate last January. According to CNN, it was "the second lowest rated GOP debate of the season, and Trump was the most-talked-about candidate without even being there."
The Trump phenomenon continues
Back when the race for the Republican nomination began, nobody thought Trump would be the last one standing. Trump, like Reagan and Schwarzenegger before him, has used his celebrity to communicate more effectively than his rivals and develop a Teflon coating that has so far protected him from his own transgressions. Rather than disparage him and his supporters, whoever runs against him in November needs to understand his communications strategy and beat him at his own game if she or he hopes to win. What is that strategy? Communicate more effectively while exploiting the weaknesses and attacking the strengths of your opponent.