COLUMBIA, S.C. - The candidates vying to replace Democratic U.S. Sen. Ernest "Fritz" Hollings know every vote counts, and apparently voters know that, too.

Long lines formed at precincts even before polls opened Tuesday and early reports indicated heavy turnout. Poll workers at one Columbia precinct said twice as many people were in early morning lines compared with four years ago.

This year's election has drawn extra attention, and the race for the Senate seat is no exception. Recent polls have shown the race tightening, with Republican U.S. Rep. Jim DeMint leading slightly over Democrat Inez Tenenbaum, the state education superintendent. But the margins of error and number of undecided voters left the outcome unpredictable.

DeMint and Tenenbaum limited their schedules Tuesday. They were scheduled to vote early in the morning and then planned to be with their families to watch the election results roll in.

The parking lot at Dent Middle School was crowded and some 200 people were waiting in line when the polls opened at 7 a.m.

"It's not normal," said 75-year-old Timothy Evans Sr., a longtime poll worker. "Four years ago we had a little over 100 voters. It's really almost double that amount."

Poll manager Diane English, who has worked at Dent Middle for 12 years agreed. When she arrived at 5:50 a.m. people already were standing in line.

"It's been like this since 7 a.m.," she said, pointing to the long line.

On Monday, DeMint and Tenenbaum barnstormed across the state, rallying supporters and perhaps influencing a few last-minutes votes.

"We're just really glad to be coming into the homestretch with this much momentum," Tenenbaum said. "If you spend the last few days just in a whirlwind tour, it lets people know you're not taking anything for granted and that you will work extra hard to get their vote."

DeMint, who crisscrossed the state visiting six airports, stood with two of South Carolina's most popular Republicans - Gov. Mark Sanford and U.S. Sen. Lindsey Graham - near a wind-swept tarmac in North Charleston.

"I think a campaign is probably the closest a man can ever come to childbirth," DeMint said. "There have been a lot of labor pains here. It has been a long, grueling experience."

South Carolina was set to make history Tuesday by either electing its first woman to the U.S. Senate or sending an all-Republican delegation to the Senate for the first time since Reconstruction - more than 100 years ago.

When Hollings went to Washington in 1966, the state was solidly Democratic. These days, it's difficult for a Democrat to win any statewide office. However, Tenenbaum, a self-proclaimed moderate, has been elected state education chief twice.

For most of the past 40 years, Republican Strom Thurmond and Hollings, had been the state's senators. Thurmond, who died last year, retired two years ago and was replaced by Graham.

The campaign has been intense, knowing control of the Senate is at stake. The state has been a battleground for both parties, which have pumped millions of dollars into the race, as well as special interest groups.

Tenenbaum has campaigned throughout the conservative-leaning state as a moderate who will act independently of her party. But Republicans have worked to pin Tenenbaum as a liberal.

Tenenbaum caught up to DeMint in the polls after several weeks of bashing the Republican's proposal to scrap the Internal Revenue Service and replace it with a 23 percent national sales tax.

That issue swayed Bob Johnson, 63, of Columbia, a retired Army veteran. "I didn't like it, I found it offensive," Johnson said.