The issue of whether President Obama was born in the United States began during his first run for office. It was initially brought up by Democrats, mostly by those who supported Hillary Clinton. Clinton never accepted the issue, and publicly stated many times that she believed President Obama was born in the US. Though he was not running for office himself, Donald Trump brought up the issue again during the second election cycle. It was an issue few believed in, but Trump persisted in raising suspicion and doubt to such an extent, Obama ultimately had the state of Hawaii release his full long-form birth certificate.
Trump considered it a victory that he could create so much doubt and suspicion in the press and by the voters. It was a victory that he could get the President of the United States to cave-in and provide documentation that he was, in fact, a US citizen. As Trump speak, this was “big league”. However, after the birth certificate was released, Trump still wanted to remain in the spotlight. Even after almost everybody else was satisfied that President Obama was a citizen, Trump continued to cause doubt and suspicion.
Trump has continued to use this tactic, and it continues to be effective for him. Make outlandish claims to raise doubt and suspicion, and have others waste their time defending the actual truth. Hillary Clinton’s email server, Ted Cruz’s father part of the JFK assassination, intelligence agencies can’t be trusted, the elections are rigged, all the major news sources are fake news, Obama wiretapping Trump Tower; all examples of Trumps ability to create doubt and suspicion.
Below is an excellent summation of Trump’s birther claims produced by CNN.