While front-runner Sen. John McCain, R-Ariz., has the GOP nomination virtually sewed up, Huckabee has the potential to undermine McCain's general election prospects, the Washington Times said, much in the same way conservative Pat Buchanan did to the first President Bush in 1992.

Former presidential speech writer Peter Robinson said Huckabee, if he stays in, "could be seeking to establish himself as a national representative of largely southern evangelicals."

Huckabee says he plans to highlight his differences with McCain on abortion and protection of marriage.

Major states still in play include Ohio, Pennsylvania, Texas, Virginia, North Carolina, Mississippi and Louisiana, the Times said.