Barack Obama's decision to publish his full birth certificate has convinced significant numbers of US voters who previously doubted that his birthplace was in Hawaii.
A new poll published by the Washington Post found that the number of those who believed Obama was born outside of the US has shrunk by half compared with a similar poll taken a year earlier.
While 20% of those polled in 2010 said Obama was not born in the US – and so possibly constitutionally ineligible to be president – the new poll, conducted on 28 April to 1 May, found just 10% thought so.
The fall was consistent throughout the political spectrum, with the percentage of self-described "conservative Republicans" saying Obama was born outside the US falling from 35% in 2010 to 16% in the 2011 poll.
The polling data also revealed a sharp rise in the number correctly identifying Honolulu and Hawaii as Obama's birthplace – rising from 48% in 2010 to 70% now. Combining that group with those whose "best guess" is that Obama was born in the US, the percentage rises to 86%.
While the so-called birthers are still out there, Obama's decision to publish his long-form birth certificate and the coverage that followed seems to have had a decisive impact in reducing the birthers to a tiny rump. While 9% of those polled in 2010 claimed there was "solid evidence" of Obama being born outside the US, now just 1% say there is.
The poll was conducted on 28 April to 1 May, with the White House publishing the full birth certificate on 27 April. And after the killing of Osama bin Laden announced on 2 May, it would be no surprise if the birther ranks shrink further.
