Probably because they doubted its existence.

(Briefing Room) — President Obama on Thursday lightened up talk of high gas prices and the budget deficit on his West Coast swing with a joke about those who question his citizenship.

“A lot of you got involved when the prospect of electing Barack Hussein Obama to the Oval Office was slim. None of you asked for my birth certificate. It was a complete leap of faith,” Obama said during a Los Angeles dinner fundraiser, drawing laughs from the crowd of his supporters.

The president appears poised to use the so-called “birther” issue to his advantage.

Billionaire businessman Donald Trump, who is flirting with running for president as a Republican, has helped revive the so-called “birther” issue in recent weeks as he has raised questions about Obama’s place of birth.