Republican presidential candidate Newt Gingrich says he's being realistic when he says Mitt Romney is "far and away the most likely" GOP nominee, but Gingrich isn't ready to drop out.

Gingrich wants to influence the party's platform, which is a statement of principles on the issues.

He's interested in promoting increased domestic oil production and personal Social Security savings accounts.

If Romney is the nominee, Gingrich says he'll do all he can to help the former Massachusetts governor defeat President Barack Obama.

Gingrich says he's glad he ran for president in hopes of bringing out new ideas, but he says it turned out to be harder than he thought.

He tells "Fox News Sunday" that he hit Romney hard, but that Romney was able to hit back even harder.