RALEIGH, N.C. — More than four times as many blacks have registered to vote in North Carolina during the first few months of 2008 as four years ago, contributing to the booming number of new voters expected to cast ballots in the state's May 6 primary.

Registrations are up overall across age, race, gender and party affiliation, and even though the traditional registration period closes Friday, observers believe the numbers will continue to surge as voters take advantage of the North Carolina's new same-day registration law.

"This year the election is so different, and so many people are excited about it," said Tahvyea Rains, 26, of Durham, who didn't vote four years ago because she didn't feel like there was a candidate for her. This year, she's backing Democratic presidential candidate and Illinois Sen. Barack Obama.

More than 45,000 blacks signed up to vote in the first three months of 2008, compared with just over 11,000 in the first three months of 2004. There were about 106,000 white voter registrations between Jan. 1 and March 31, compared with 47,000 four years ago.

Clyde Frazier, a professor of political science at Meredith College in Raleigh, said the larger jump in black registrations likely indicates growing support for Obama, who has won a string of Southern states with large numbers of black voters.

Blacks have historically accounted for about one-third of voters in North Carolina's Democratic primary.

"I think everybody's expecting it to be higher than that this year," Frazier said.

More of the new voters registered as Democrats, with the number nearly tripling from 2004 to 74,590. Republican registrations more than doubled to 41,301, while more than 49,558 unaffiliated voters signed up, compared with just 16,858 in the first three months of 2004.

There were less than 5.1 million people registered to vote in May 2004, compared with more than 5.7 million today. The Democratic presidential race was over early by comparison to this year, with North Carolina Sen. John Edwards bowing out to Sen. John Kerry of Massachusetts after the March 2 Super Tuesday elections.

But this year, the North Carolina primary could be critical to the fortunes of Obama and his Democratic rival, New York Sen. Hillary Rodham Clinton.

"The energy of both campaigns has sparked the interest of many folks who might not of registered to vote before," said Mike Trujillo, Clinton's North Carolina field director.

The campaigns continue to ramp up their efforts to draw in new voters ahead of the state primary, which will divide 115 delegates between the candidates — the last triple-digit delegate count before this summer's Democratic Party convention in Denver.

Trujillo said the Clinton campaign has placed a heavy focus on a new advertising campaign that asks prospective voters to submit questions to Clinton through a Web site. Thousands have responded — connecting the campaign with many uncommitted and unregistered voters, he said.

The Obama campaign launched several voter registration initiatives in the past few weeks, bringing in singer Tatyana Ali to lead registration drives and launching a competition that awards the leading registration recruiters a meeting with Obama.

"It's not enough that you're registered. It's not enough that you're fired up and ready to go," Obama's wife, Michelle, said during a speech this week in Winston-Salem. "All of you know about 20 trifling people in your lives, that after a whole long year, still don't know there's a presidential election coming up. You have to pick up the phone."

Both campaigns plan a heavy focus to building the already strong numbers by using North Carolina's new one-stop voting law, which allows voters to register and vote on the same day beginning April 17.

"The flood of new registrants is not over," Frazier said. "These campaigns will continue to try and get people to register and turn out."