Why is Ben Carson dropping in the polls?

U.S. Republican presidential candidate Ben Carson speaks at a campaign event in Pahrump, Nevada November 23, 2015. REUTERS/David Becker - RTX1VI7W
REUTERS

CBS News is answering some of the most-Googled questions about the 2016 Republican presidential candidates ahead of Tuesday night's Republican debate.

Former neurosurgeon Ben Carson was the first candidate to overtake businessman Donald Trump in polls of both voters nationwide and voters in Iowa in late October. But in the next six weeks, that lead slipped away and now he sits behind both Trump and Texas Sen. Ted Cruz.

That's because Carson has lost ground key voting groups in Iowa: evangelicals, Tea Party supporters, those who are very conservative and older voters. Much of that support has actually gone to Cruz, helping boost him into first place.

The polls don't tell us exactly why those voters have abandoned Carson, but once he took the lead, news outlets took note of some of his pronouncements, like his claim that he had been offered a full scholarship to West Point or the idea that pyramids were used for grain storage.

after the terror attacks in Paris highlighted the threat from the Islamic State of Iraq and Syria (ISIS) - and Carson's foreign policy credentials began looking weak compared to his rivals.

The former neurosurgeon and political newcomer has made some questionable comments on international affairs, like his assertion in one Republican debate that the Chinese are in Syria. The New York Times subsequently reported that tutoring Carson on foreign policy issues had been difficult. Carson has since gone to visit Jordan to see the Syrian refugee crisis firsthand, and he also plans to go to Nigeria, Kenya and Zambia this month.

Coverage of the Republican debate begins at 6 p.m. ET for lower-tier candidates and 8:30 p.m. for the main debate.

  • Rebecca Kaplan

    Rebecca Kaplan is a political reporter for CBSNews.com.