Nearly half of usual Republican primary voters in Iowa think President Obama was not born in the United States, while barely one-quarter believe he was, according to a PPP poll released on Tuesday.

In the poll, 48% of registered Republican voters said Obama was not born in the U.S., while 26% said he was. Additionally, 26% said they were unsure.

That percentage is actually slightly better than the national average for typical Republican primary voters, a majority of whom believe Obama was born outside the U.S. In February, a PPP poll found that 51% of registered Republican voters said Obama was not born in the U.S., compared to 28% who said he was, and 21% who were unsure.

However, the high birther base does not necessarily mean that the issue will be critical in determining which candidate wins Iowa. Donald Trump, who has vaulted to the front of several polls through a media blitz in which he's repeatedly questioned Obama's birth, placed a modest third in the poll's hypothetical primary election. While 19% of voters who doubted Obama's citizenship backed Trump, 25% broke for Huckabee.

The PPP poll was conducted April 15-17 among 419 registered Republican voters. It has a margin of error of 4.8%.

Republished with permission from Authored by Jon Terbush. Photo via AP. TPM provides breaking news, investigative reporting and smart analysis of politics.