Trump is running a populist campaign, appealing to people who feel politically disenfranchised. He is cashing in on a wide range of anxieties and has turned that into so much popular support that the republican party has essentially been forced to allow him as their nominee, because if they didn't, the party would lose a lot of power. He is mostly aligned with the right on immigration and taxes, and on most other issues his range of beliefs is everywhere from moderate liberal to extremely right wing.
Campaigns like Trump's are hard to gauge, but it does appear that he will be competitive in November. A 24% chance at victory can translate into a very tight race, depending the distribution of his support. He has alienated many minorities and depressed the republican establishment a bit, but he has also energized a lot of poor white people and a reasonable number of independents. As always, the swing states are going to be incredibly important, but this is an area where Trump has so far suffered.