WASHINGTON – Republicans renewed their grip on the Senate on Tuesday night and reached out for more, capturing Democratic seats across the South. Democratic leader Tom Daschle faced a strong challenge in South Dakota.

With Republicans assured of 52 seats in the new Congress – one more than the current Senate – races also were still unsettled in Florida, Colorado and Alaska.

Democratic State Sen. Barack Obama easily captured a seat formerly in Republican hands in Illinois, and will be the only black among 100 senators when the new Congress convenes in January. “I am fired up,” he told cheering supporters in Illinois.

Obama, 43, first gained national prominence this summer when his Kerry tapped him to deliver the keynote address at the Democratic National Convention.

Elsewhere, Republicans were more likely to be celebrating.

“It looks like we’re going to have a much strengthened Republican majority,” predicted Sen. George Allen of Virginia, chairman of the GOP senatorial committee.

Rep. Johnny Isakson claimed Georgia for the Republicans, and Rep. Jim DeMint took South Carolina. Rep. Richard Burr soon followed suit in North Carolina. In each case, Democratic retirements induced ambitious young members of Congress to give up safe House seats to risk a run for the Senate.

Isakson, who replaced former House Speaker Newt Gingrich in Congress in 1999, coasted to victory in Georgia. He triumphed over Rep. Denise Majette in a campaign to replace Sen. Zell Miller – a Democrat who crossed party lines to deliver a memorably anti-Kerry speech at the Republican National Convention.

Arlen Specter won re-election in Pennsylvania with barely 50 percent of the vote in a multicandidate field.

In Louisiana, Republican Rep. David Vitter led several Democratic rivals comfortably with more than 90 percent of the precincts counted, and flirted with an outright majority that would allow him to avoid a Dec. 4 runoff.

In Oklahoma, a state where Democrats long touted their chances, former Rep. Tom Coburn captured the votes of three-fourths of the president’s supporters. That was enough to trounce Rep. Brad Carson and keep the seat in GOP hands.

Most veteran lawmakers of both parties coasted to new terms after campaigns against little-known and poorly funded opponents.

But there were exceptions.

Daschle and former Rep. John Thune were in an impossibly close race with votes counted in one-third of their sparsely populated state – separated by fewer than 1,000 votes. Theirs was a campaign on which the two men spent $26 million – an estimated $50 for each registered voter.

After a particularly caustic campaign in Kentucky, Republican Sen. Jim Bunning, 73, fell behind Democrat Dan Mongiardo early in the evening before moving ahead and winning a new term in Kentucky.