From: "How The Right Lost Its Mind"
For many on the Right, the ur-conspiracy theory of the Obama presidency was the notion that Obama had not been born in the United States and was therefore not constitutionally eligible to be president. An entire cottage industry of “birthers” sprang up, complete with elaborate attempts to document the “evidence” that Obama was, in fact, a secret Kenyan. Arguably, Donald Trump launched his successful presidential bid by seizing upon the issue, which he milked for the maximum amount of publicity. Trump would eventually disavow birtherism in the final months of the 2016 campaign, while attempting to blame its origins (falsely) on his rival Hillary Clinton. But for five years, Trump had questioned Obama’s birthplace.
In March 2011, Trump appeared on the Laura Ingraham Show to declare: "He doesn't have a birth certificate, or if he does, there's something on that certificate that is very bad for him. Now, somebody told me -- and I have no idea if this is bad for him or not, but perhaps it would be -- that where it says 'religion,' it might have 'Muslim.' And if you're a Muslim, you don't change your religion, by the way." On CNN, he escalated his rhetoric, saying that “if he wasn’t born in this country, he shouldn’t be the president of the United States.” After Obama produced the certificate in April 2011, Trump briefly acknowledged his legitimacy, but quickly seemed to recant, saying “a lot of people do not think it was an authentic certificate.”
To be sure, some conservatives with megaphones denounced the birthers. Early on, talk show host Michael Medved called the movement’s leaders “crazy, nutburger, demagogue, money-hungry, exploitative, irresponsible, filthy conservative imposters” who had become “the worst enemy of the conservative movement.” Birtherism, he said, “makes us look weird. It makes us look crazy. It makes us look demented. It makes us look sick, troubled, and not suitable for civilized company.”
But despite repeated attempts to debunk the theory, many leading Republicans either stayed silent or refused to forcefully denounce the theories that were springing up. One reason for their reluctance was that “birtherism” was not fringe notion in the GOP. A Public Policy Poll in February of 2011 found that birthers had become a majority among likely Republican primary voters -- 51% said they did not think Barack Obama was born in the United States. Less than a third of GOP voters -- 28 percent – said they firmly believed that he was born here, while 21 percent weren’t sure.