WASHINGTON - Former Arkansas Gov. Mike Huckabee announced plans yesterday to form a presidential exploratory committee, hoping to carve out a conservative niche in an increasingly crowded field of Republican candidates.

The onetime Southern Baptist minister, perhaps best known for losing 100 pounds in two years, said he would file papers today with the Federal Election Commission, enabling him to start raising money.

"I think America needs positive, optimistic leadership to kind of turn this country around, to see a revival of our national soul," Huckabee said on NBC's Meet the Press.

Huckabee enters the race as a long shot, boasting little national name recognition and up against such high-profile and well-funded Republican candidates as Sen. John McCain of Arizona, former Massachusetts Gov. Mitt Romney and former New York Mayor Rudolph W. Giuliani.

Like Sen. Sam Brownback of Kansas and Rep. Duncan Hunter of California, Huckabee is hoping that the GOP's traditional base is not content with the current leaders in the race and that there might be room for a staunch conservative who opposes abortion and gay marriage.

Huckabee, 51, said yesterday that he supported President Bush's position on the Iraq war, and he discussed his record in Arkansas, which was not always predictable. He advocated for providing state services for illegal immigrants, opened up insurance benefits for 70,000 children from low-income homes, and raised taxes several times, drawing criticism from fiscal conservatives.

He also publicly supported creationism, a philosophy advocated by fervent Christians, arguing that students should be exposed to the study of the doctrine as well as evolution.

Huckabee was Arkansas lieutenant governor in 1996 when Democratic Gov. Jim Guy Tucker was convicted of conspiracy and mail fraud relating to the Whitewater scandal. He rose to governor when Tucker resigned, and subsequently was elected by large margins for two more terms in the historically Democratic state.

The former governor shares his birthplace with another governor of Arkansas who ran for president, Bill Clinton. Both men were born in the small town of Hope.

As Arkansas governor, Huckabee admitted to weighing 300 pounds. After being diagnosed with diabetes in 2003, he went on a public diet, and started competing in marathons. He lost more than 100 pounds.

Huckabee, who also spoke yesterday at the Conservative Summit in Washington, said he planned to be in Iowa, the site of the first 2008 caucuses, tomorrow and Wednesday.