DES MOINES, Iowa — The Republican presidential race has gone from merely unpredictable to chaotic.

As the first votes are cast Thursday, contests are tight in many states. Most GOP candidates have seen their fortunes shift in the homestretch. No one has a clear path to the nomination.

Mike Huckabee recently emerged as a serious contender after rallying restive conservatives in must-win Iowa and elsewhere. The ex-governor of Arkansas, however, lacks the money and manpower of his better-known opponents.

Mitt Romney's wealth bought him enough visibility to maintain comfortable leads in Iowa and New Hampshire for months. But the former Massachusetts governor's early-state strategy now is threatened; he is fighting battles in both states.

Rudy Giuliani long dominated national polls only to watch his standing suddenly drop. The former New York mayor faces several likely early defeats and can only hope his unorthodox approach works — winning delegate-rich states that vote later.

John McCain, the U.S. senator from Arizona whose campaign all but imploded over the summer, is looking for a New Hampshire win to propel him in states beyond.

Fred Thompson, the former U.S. senator from Tennessee and TV actor whose campaign performance didn't live up to months of hype, wants to place in the top three in Iowa to prove he is credible.

Ron Paul, a Texas congressman with a libertarian streak and anti-war tilt, can't be discounted. He's raised an astounding $18 million in less than three months and could be a spoiler.

Many Iowa and New Hampshire voters wait until the final days to pick a candidate, and late-deciders could break for anyone.

Other unknowns further muddle the race: It's unclear whether voters will punish Romney for negative advertising. Immigration has proven the most divisive issue all year, and religion has emerged as a fault line in recent weeks. Unexpected outside events, such as the assassination of former Pakistani Prime Minister Benazir Bhutto, could shift the dynamics.

Here's how the race stands:

Iowa: Jan. 3

It's a dogfight in the Midwestern state that votes first and has 40 GOP delegates. Huckabee and Romney are going at each other for the top spot in what is essentially a two-way contest.

Romney methodically built a high-powered organization, courted voters with face-to-face politicking and introduced himself through $5 million in TV ads this year. He had a comfortable lead in Iowa for months.