GRAND RAPIDS, Mich. (AP) — One Republican presidential nomination. Two primaries.

Mike Huckabee, Mitt Romney and Fred Thompson are competing for the love of Republicans on the right, while John McCain and Rudy Giuliani battle for the loyalty of the party's center.

The GOP is ideologically split and so, too, the Republican race to succeed President Bush. It's almost as if there are two separate Republican primary campaigns going on at the same time.

By most strategists' accounts, the candidate who can unite all wings of the party will be the nominee.

"The fight over who wins the conservatives is up in the air, just as the fight over who wins moderates is up in the air," said Terry Nelson, a veteran of Bush's bids and a one-time McCain campaign manager. "The question is whether that will be the dynamic in a few weeks."

Both factions will meet head-on in Michigan on Tuesday when Romney and McCain compete in a rematch of their New Hampshire tussle. In New Hampshire, McCain won among moderates and independents — despite his strong right-leaning Senate voting record — while Romney had an edge with hard-core conservatives.

The separate ideological races could shake out soon: South Carolina votes Jan. 19, followed by Florida 10 days later.

"There's no doubt that South Carolina appears to be the final primary for the religious conservatives inside the Republican nomination process, and that's between Thompson, Romney and Huckabee," said Greg Strimple, a Republican strategist in New York who has no allegiance in the race. "The final centrist primary may be held in Florida between Giuliani and McCain."

The results, he argued, could set up a championship of sorts on Feb. 5, with the candidate of the right and the candidate of the center competing for the party nod.

Even then the outcome could be mixed, he cautioned, given that Southern Bible Belt states, more moderate coastal states like California and New York and many others vote on that Tuesday.

An Associated Press-Yahoo poll in December shows about a quarter of Republicans and people who lean toward the GOP call themselves moderates, while 46 percent call themselves "somewhat conservative" — with a big swath willing to break either toward the right or the center — and 23 percent call themselves "very conservative."

Polls show Romney, Huckabee and Thompson scoring better among conservatives and pulling votes from one another, while McCain and Giuliani outpace the others among moderates, likewise sharing support.

Here's how the candidates stack up in what could amount to pre-Feb. 5 semifinals.

For the right:

—Romney, the former Massachusetts governor, long has sought the mantle of most conservative Republican. He has shifted to the right on various issues and reversed his stance on abortion rights; he now opposes them. He courted conservatives by emphasizing his opposition to abortion and gay marriage, and he aggressively made his case to Christian evangelicals to overcome concern about his Mormonism. He lost in Iowa and New Hampshire, and wants to rebound in Michigan next week, just before South Carolina votes.

—Huckabee, the former Arkansas governor, won Iowa's caucuses. The former Southern Baptist minister's surprise victory was fueled by religious conservatives. Religion — and his rock-solid opposition to abortion and gay marriage — was a focus of his campaign. Huckabee could appeal to evangelicals in western Michigan, and his economic populism also could resonate in Reagan Republican country outside Detroit. He's more focused on South Carolina.

—Thompson, the former Tennessee senator, tried to answer restive Republicans' calls for an authentic conservative. He has billed himself as the most consistent candidate in the field, but he has failed to catch fire. The laid back Tennessean senses opportunity in South Carolina and has planted himself there in hopes of reviving his bid. He's looking to capitalize on his better-than-expected third-place showing in Iowa.

For the center:

—McCain, the Arizona senator, has a solidly conservative voting record, but many GOP voters perceive him to be more of a centrist because of his independent streak and willingness to buck hard-line conservatives on issues like immigration. With a bipartisan pitch and straight-shooting image, McCain appeals to all types of voters. Independents in New Hampshire twice have powered him to victory. This year, as Giuliani has dropped off, moderates and independents have broken McCain's way.

—Giuliani, a former New York mayor, is the only candidate who backs abortion rights and gay rights. That — as well as his three marriages — undercut his effort to position himself as conservative on most issues. A loser in the first three contests, Giuliani has pinned his hopes on a Florida win to challenge whoever is still standing on Feb. 5.

It's a bit of a muddle one week into the voting.

"Has the Republican Party digested all that's happened in the past week and settled on a direction? The answer is no," said Phil Musser, a Republican strategist who supports Romney. "So you have a very healthy process, but a very fractured party."