The latest U.S. public opinion polls show Newt Gingrich in the lead among Republican contenders for next year's presidential election.

A Quinnipiac University survey released Tuesday shows Gingrich with 26 percent support among likely Republican voters. Former Massachusetts governor Mitt Romney is not far behind with 22 percent, while 14 percent of those surveyed favor Georgia businessman Herman Cain, and the rest of the field trails in single digits.

When limiting the choice to just the two front-runners, Gingrich and Romney, the difference is even larger. Forty-nine percent of those surveyed selected Gingrich, compared to 39 percent for Romney. But when it comes to the candidate with the best chance to defeat President Barack Obama, Republican voters pick Romney over Gingrich.

Gingrich also surged into first place in two other national polls — a CNN/Orc International survey, and a joint poll by the USA Today newspaper and the Gallup Organization.

The Republican presidential contenders will have a chance to collect more support Tuesday night when they gather in Washington for a two-hour televised debate. The discussion will focus on foreign policy and national security issues.

The latest polling marks a huge drop in support for Cain, who had been seen as a top rival to Romney until recently when he was forced to respond to allegations of sexual harassment dating back to the late 1990s.

Cain also had some awkward moments on foreign policy, including a brief memory lapse when asked to comment on President Obama's policy on Libya.