Former U.S. House of Representatives Speaker Newt Gingrich is solidifying his lead among Republican contenders in the 2012 race for the White House.

Gingrich has pulled ahead of former Massachusetts Governor Mitt Romney in several national opinion polls and in important early voting states.

One of those states is Iowa, which holds the first vote in the Republican nomination battle with its caucuses on January 3.

A new ABC News-Washington Post survey shows Gingrich with 33 percent support among likely Republican caucus-goers in Iowa. Romney and Representative Ron Paul of Texas tied for second with 18 percent each. The poll also shows more Iowans trust Gingrich most to handle the economy.

In South Carolina, Gingrich tops Romney 38 percent to 22 percent in a new poll released Tuesday by Winthrop University. Texas Governor Rick Perry placed third with 9 percent.

Gingrich has surged in opinion polls as businessman Herman Cain lost support following allegations of sexual harassment and an extramarital affair. Cain dropped out of the race on Saturday.