The Trump factor continues to be the biggest wildcard in the race for the GOP presidential nomination.

GOP presidential front-runner Donald Trump speaks at a news conference in Manhattan on September 3, 2015 in New York City. (Photo by Spencer Platt/Getty Images)

What many can't figure out is how far Donald Trump is willing to go. Most speculate he will eventually drop out of the race when he loses interest, and many think he's just running for fun.

But with now 30 percent support among GOP voters, far more than any other candidate, some close to Trump say he believes he can win the nomination and go on to actually be president.

And Trump is doing this with his own money, not forced to pander to special interests to fund his run.