Poll: 45 percent of Republicans think Obama born out of US

A plurality of Republicans believes that President Obama was not born in the United States, according to a new poll released Thursday. 

Forty-five percent of registered Republicans think Obama was born outside the U.S., 33 percent believe he was born in the U.S. and 22 percent don't know, per the results of a CBS News/New York Times survey. 

The issue of Obama's birthplace has reemerged with Donald Trump's flirtation with a run for the GOP nomination for president. Trump has raised questions about the validity of Obama's birth certificate, which his campaign released in 2008 to prove that he was born in Hawaii. 

Republicans worry the issue could end up hurting their party and helping Democrats. Arizona Gov. Jan Brewer, a Republican, this week vetoed legislation approved by her state's legislature that would have forced presidential candidates to prove their citizenship in order to get on the state's ballot. 

Obama last week addressed the "birther" question, calling it an effort by Republicans to attack him politically.

"[It creates] think a problem for them when they want to actually run in a general election where most people feel pretty confident the president was born where he says he was, in Hawaii," Obama said of some Republicans. "He — he doesn’t have horns … we’re not really worrying about conspiracy theories or — or birth certificates."

Only 23 percent of registered voters surveyed in the CBS/Times poll see Trump as a serious candidate.

The poll surveyed 1,224 adults by telephone interview between April 15-20. The margin of error is 3 percentage points. It also included an oversample of 543 Republicans. That sample had a margin of error of 4 percentage points.

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