What remains is a quintessentially Trumpian endeavor that blurs the line between campaigning and brand-building and complicates Mr. Trump’s claims that he is funding his own White House campaign. About three-quarters of Mr. Trump’s total campaign spending has either gone to reimburse his own businesses or has been covered by funds from grass-roots donors, according to an analysis by The New York Times of F.E.C. reports. Virtually all of the money Mr. Trump himself has put into the campaign was lent, rather than donated outright, meaning that he could potentially sell enough hats and T-shirts to pay himself back down the road.