Senate Minority Leader Thomas A. Daschle (D) continued to slip further behind his Republican challenger early this morning, trailing by nearly 9,000 votes with 94 percent of the precincts reporting in South Dakota.

The Senate race was still too close to call as of 3 a.m. with about 50 precincts yet to officially record results, though President Bush had already pulled away with South Dakota's three electoral votes. With nearly 365,500 ballots counted, Daschle was steadily losing ground as an earlier virtual dead heat widened to 2.5 percent. Neither side was willing to declare a victor.

Daschle's race against challenger John Thune (R), a former member of the U.S. House, has been an all-out battle, with the two candidates spending more than $40 million in a seesaw of bitter political advertising that has dominated the local airwaves. Daschle's apparent vulnerability has made South Dakota's race central to the fight for control of the Senate and has lured massive national efforts to keep him in his seat, and to push him out.

"It comes down to a simple idea," said Dan Pfeiffer, Daschle's campaign spokesman. "South Dakota now sits at the front of the line. Do we want to stay there, or do we want to go to the back of the line?"

Daschle is the first member of the Senate leadership from lightly populated South Dakota, which now enjoys a relatively significant amount of power on the national political scene. Daschle has won his three Senate terms in the heavily Republican plains state by carrying nearly 20 percent of the GOP vote, a group of voters he is relying on to send him back to Washington.

Should Daschle fail, he would be the first Senate leader to lose a reelection campaign since Republican Barry Goldwater unseated Senate Majority Leader Ernest W. McFarland (D-Ariz.) in 1952, winning by just 7,000 votes.

Thune's advisers were cautiously optimistic early this morning, but they shied away from calling the race even as cheers could be heard in the background of a telephone interview: "I feel like the map is still going in our favor, but we're not ready to declare victory," said Dick Wadhams, Thune's campaign manager. "The math is looking better and better for Thune."

Daschle's rise to the Democratic leadership has played on both sides of the argument, as Thune has said the senator has lost touch with the 750,000 residents of South Dakota while deferring to Washington politics. Daschle's camp says he has his interests firmly rooted in the prairie, using his power on Capitol Hill to bring federal funds for drought aid, highway funding and subsidies for corn-based ethanol.

"He says one thing in South Dakota, but he does another thing in Washington," Wadhams said.

Once the popular lone representative from South Dakota, Thune lost the 2002 Senate race to Tim Johnson (D) by just 524 votes, despite the strong backing of the president and the Republican Party. Thune has been pounding on Daschle this year in a bid that Republicans hope will topple one of the nation's top Democrats.

Early estimates last night had the race in a dead heat in a state that customarily sees nearly 70 percent of the population casting ballots. As more votes were counted, Daschle opened up a 52 percent to 48 percent lead by 10 p.m., but that lead quickly disappeared as the candidates pulled almost even an hour later with about 335 precincts still to report their tallies. Daschle and Thune were separated by 250 votes with more than 102,000 votes counted, and Thune took a slight lead just prior to midnight before continuing to pull away.

Daschle, 56, was first elected to the U.S. House in 1978, nine years after he graduated from South Dakota State University. After four terms in the House, he won his first Senate race in 1986. He was reelected in 1992 and two years later succeeded George Mitchell as Democratic leader. He was elected to a third Senate term in 1998.

Republicans have accused Daschle of leading efforts to block the Bush administration's agenda, and he has had to walk a thin line because of his large Republican constituency back home. A frequently run TV ad in South Dakota, financed by the National Republican Senatorial Committee, has shown footage of Daschle in 2003 criticizing the diplomatic approach to the war in Iraq, saying that he led "the Democratic attack on President Bush."