That's not really true. Just the way the electoral college is setup, Democrats have a strong structural edge over Republicans. It's certainly possible for Republicans to win, but they have an uphill battle just by virtue of how each state leans politically.
Trump is smart.
The Republicans have zero chance of winning the black vote. American blacks vote so uniformly Democrat, that it's impossible to make a dent there. The so called 'hispanics' mainly vote for those who will allow everyone into the US, which the democrats have no problems with.
Therefore, the only chance the Repubs have of winning is to take the entire white vote.
Keep in mind, Obama got elected with a huge number of whites. In particular young whites and female whites.
Trump does what is needed, he is going after the vast white middle class that is feeling the squeeze by immigration and NY bankers. He needs to win the female white vote on economics over emotional crap like abortion and 'equal pay'.
That is the only success recipe for the repubs.
The other repubs won't do this, because they're aligned to so many special interest groups, the big biz groups which like downward wage pressure, the jewish groups, which prefer a multi-cultural US, the Cuban groups in Florida with lots of monies.
Trump is clever though, he is taking a very hard stance on Iran, which is something the Democrats won't do. By doing this, he is forcing the hand of the jewish media. What do you value most? The security of Israel or your dreams of a multi-cultural America? He is saying: Time to pick one, which is most important to you?
By doing so, he is A) getting the white vote and B) getting the jewish vote/money.
I am still not convinced Trump is for real in his intent to actually run, but it is very good entertainment. It would be great with a ballot of Trump/Rand.
If nothing else, Trump is showing the GOP for what they are, a bunch of cronies beholden only to special interest groups.