Why does Donald Trump keep saying Obama was born in Kenya, when even Obama has stopped claiming that?

Why does Donald Trump keep saying Obama was born in Kenya, when even Obama has stopped claiming that? | The Daily Caller
It’s just silly. Obama was born in Hawaii. It’s over, Birthers. But Donald didn’t get the memo. In an interview with the Daily Beast published today, he said:
“Look, it’s very simple,” said Trump, who has spent the past 13 months questioning Obama’s constitutional eligibility to occupy the White House (and only doubled down with his stubborn skepticism after Obama produced a long-form birth certificate, certifying he was born on Aug. 4, 1961, in Hawaii, and then hilariously roasted him at the 2011 White House Correspondents Dinner).

“A book publisher came out three days ago and said that in his written synopsis of his book,” Trump went on, “he said he was born in Kenya and raised in Indonesia. His mother never spent a day in the hospital.”