American Carnage: On the Front Lines of the Republican Civil War and the Rise of President Trump by Tim Alberta:
He was a latecomer to the birther movement. In fact, he had first commented publicly on Obama’s citizenship just a month earlier, during an interview with ABC’s Good Morning America. Trump called the circumstances surrounding Obama’s birthplace “very strange,” adding, “The reason I have a little doubt—just a little—is because he grew up and nobody knew him.”
This was not true. Obama’s upbringing on the big island was thoroughly documented by friends and family members, not to mention verified by journalists and academics. But that didn’t stop Trump from peddling falsehoods, with increasing certainty, in the days that followed. On ABC’s The View, he asked “Why doesn’t he show his birth certificate? There’s something on that birth certificate that he doesn’t like.” On Fox News, he said Obama “spent millions of dollars trying to get away from this issue.” On Laura Ingraham’s radio show, he said of the certificate, “Somebody told me . . . that where it says ‘religion,’ it might have ‘Muslim.’” And on MSNBC’s Morning Joe, Trump announced that Obama’s “grandmother in Kenya said, ‘Oh, no, he was born in Kenya, and I was there, and I witnessed the birth.’ Now, she’s on tape. I think that tape’s going to be produced fairly soon.”
In fact, the tape features Obama’s grandmother stating repeatedly that she did not witness the future president’s birth because it occurred in Hawaii and she lived in Kenya. But facts had never stood in the way of conservatives’ theorizing about Obama’s shadowy past: How he was raised by his radical father (who actually had abandoned the family when his son was two years old); how he inherited an anticolonial bias from living in Kenya (he spent part of his childhood in Indonesia after his mother remarried); how he was a Muslim (despite being baptized in 1998 and writing extensively about accepting Christ after being raised by his nonbelieving grandparents).
Trump would later claim that he never truly believed that Obama was born outside the United States. But Boehner, a frequent golfing buddy, says Trump absolutely did. “Oh yes. Oh yes. He wouldn’t have sent people to Hawaii and do the investigation if he didn’t believe it.”