Super Tuesday voting under way in 24 U.S. states

By John Whitesides, Political Correspondent

Republican Mike Huckabee claimed the first win on Tuesday with a victory in West Virginia, one of 24 states holding nominating contests on "Super Tuesday" that will yield a huge haul of delegates to this summer's conventions to nominate the two candidates for the November presidential election.

Economic concerns -- plunging housing values, rising energy and food prices, jittery financial markets and new data showing a big contraction in the service sector -- have eclipsed the Iraq war as voters' top concern, opinion polls show.

"The fact that we've made so much progress I think indicates that we've got the right message," Obama said on NBC's "Today" show.

At the West Virginia convention, Romney led after the first round of voting but was short of the majority needed for a win. Romney, a former Massachusetts governor and venture capitalist, told the convention he was the best candidate to handle a troubled economy and uphold conservative principles.

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Huckabee aimed for a strong showing in the South with its concentration of evangelical Christians.

Clinton and Obama have split the first four significant contests and spent heavily on advertising from coast to coast.

Clinton voted in suburban New York, accompanied by her husband, former President Bill Clinton. Obama headed back to Illinois after a round of television and radio interviews.

In contrast, many of the 21 Republican contests are winner-take-all when awarding delegates, meaning a strong day by McCain could give him a commanding lead.

McCain predicted victory at an early-morning rally.

In duelling commercials, McCain and Romney both invoked former President Ronald Reagan in an attempt to question each others' conservative credentials.

(Additional reporting by Jeff Mason, Claudia Parsons, Steve Holland, Ellen Wulfhorst, Andy Sullivan; Writing by Andy Sullivan; editing by Deborah Charles)