Lured by the political duel between Barack Obama and Hillary Rodham Clinton, North Carolina voters are registering to vote in the May 6 primary in record numbers.

North Carolina has netted at least 110,000 new voters so far this year, with a particularly sharp rise among unaffiliated voters, Democrats and black people, according to the State Board of Elections.

"It started back in late December," said Johnnie McLean, the deputy state elections director. "It's obviously due to the presidential primaries."

There is also anecdotal evidence that some Republicans are switching their registration to Democrat or unaffiliated to participate in the primaries. McLean said she has received a number of inquiries, although there are no hard statistics available on whether it is a significant trend.

North Carolina is following a national pattern. There have been sharp increases in voter registration and voting in earlier primaries. Democratic voter interest has risen because of the close and extended competition between two historic candidates, Obama and Clinton.

The Obama campaign has launched an intensive registration drive across North Carolina that has reached a pitch this week, with the approach of Friday's deadline for registering to vote on Election Day.

On college campuses, at shopping centers, in high schools, in restaurants and in newly rented storefront campaign offices, registration efforts are under way.

"We plan to make a last-minute aggressive push across the state," said Steve Hildebrand, Obama's deputy national campaign manager. "It's a very important state."

The Clinton campaign is taking a different tack. It is focusing on a new North Carolina law allowing those who cast early absentee ballots -- during the period between April 17 and May 3 -- to register and vote the same day at early voting stations.

That way voters can be registered and taken to the polls on the same day.

"From an efficiency standpoint, we are going to be running one of the most aggressive voter registration efforts in North Carolina history," said Mike Trujillo, Clinton's state field director, who played a similar role in California and Texas.

The Obama campaign said it also plans to use early voting widely.

The registration drives are being conducted by various means -- old-fashioned neighborhood canvassing, registration tables at shopping centers, Internet registration forms on the computer, and even in television ads.

"Register to Vote Now" is the message that flashes across the screen in the Obama ad, featuring photographs of the Iraq war and a pollution-belching smokestack.

The Clinton ad is more subtle. It features the candidate asking people to submit questions to be answered in future ads. The commercial has provided her campaign so far with 7,000 contacts of North Carolinians.

Dozens of events

The Obama factor is widely credited with greatly increasing Democratic voter turnout in earlier primary states, attracting large numbers of young voters, independents and African-American voters. The Obama campaign thinks North Carolina will be no different.

"Expanding our base is very important," said Hildebrand, who said enthusiasm for Obama has doubled and even tripled turnout in some early primary states.

Last weekend more than 1,000 Obama volunteers worked registering Tar Heel voters, Hildebrand said.

The Obama Web page lists 50 events in North Carolina, Wednesday through Friday, most of them involving voter registration efforts.

Today, actress and singer Tatyana Ali, at the request of the Obama campaign, will visit college campuses across the state including in Raleigh and Durham urging students to register.

The Clinton campaign believes it can go toe-to-toe with the Obama campaign in getting voters registered and to the polls.

Both campaigns have set up field networks across the North Carolina.

The Obama campaign says it has 21 offices and that number continues to grow. The Clinton campaign has five offices, but campaign officials expect that number to grow to between 17 and 20 offices.

The number of campaign staffers -- from veterans of other states to local hires -- has not been disclosed. But the campaigns each have dozens of organizers in the state with more on the way who are designed to register and get their supporters to the polls.

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