Huckabee told NBC's Tim Russert on "Meet the Press" he is setting up an exploratory committee in what may turn into a full-fledged effort to win the nomination.
Conservative groups have criticized Huckabee for raising taxes in Arkansas.
"I wouldn't propose any new taxes," Huckabee said. "I wouldn't support any, but if we're in a situation where we are in a different level of war, where there is no other option, I think it's a very dangerous position to make pledges that are outside the most important pledge you make, and that is the oath you take to uphold the constitution and protect the people of the United States."
Huckabee once said, "I hope we answer the alarm clock and take this nation back for Christ."
But he told Russert Sunday, "I think it's dangerous to say that we are a nation that ought to be pushed into a Christian faith by its leaders ... (but) I make no apology for my faith. My faith explains me."
Huckabee said he would support legislation outlawing abortion, even in cases of rape and incest, except to save the life of the mother.