Obama's defeat came as he had appeared to be within reach of gaining an endorsement from the powerful Culinary Workers union in Nevada in the days ahead. He is still strong in South Carolina, where the Democratic electorate is heavily black and likely to go for the most viable black presidential candidate in history.

The Republican race turns next to Michigan, where McCain and Romney already are advertising on television, and where both men planned appearances today. Huckabee also was expected to campaign in the state.

According to preliminary results of a survey of voters as they left their polling places, more independents cast ballots in the Democratic race than in the Republican contest. They accounted for four of every 10 Democratic votes and about a third of Republican ballots. The survey was conducted for The Associated Press and the television networks.

Republicans were split roughly evenly in naming the nation's top issues: the economy, Iraq, illegal immigration and terrorism. Romney had a big lead among those naming immigration, while McCain led on the other issues.

Half of Republicans said illegal immigrants should be deported, and this group leaned toward Romney. Those saying illegal immigrants should be allowed to apply for citizenship leaned toward McCain, while the two candidates split those saying those here illegally should be allowed to stay as temporary workers.

Among Democrats, about one-third each named the economy and Iraq as the top issues facing the country, followed by health care. Voters naming the economy were split about evenly between Obama and Clinton, while Obama had an advantage among those naming the other two issues. Clinton has made health care a signature issue for years.

About one-third said if Bill Clinton were running, they would have voted for him on Tuesday.

---

Contributing: Liz Sidoti, Nedra Pickler, Scott Lindlaw, Glen Johnson, Beverley Wang, Charles Babington, Holly Ramer and Clarke Canfield