Democrats scored big victories in the battle to control the U.S. Senate, but party hopes for a new majority were put on hold Wednesday as the key seat for majority remained too close to call.

After a full night of vote-counting, much of it by hand, Democratic challenger Jon Tester was declared the victor over Republican Sen. Conrad Burns in Montana. Burns lost by about 3,100 votes. That brought the vote tally for the Senate to 49 Republicans, 48 Democrats and two independents who will caucus with Democrats.

During the night, Republican Sen. Jim Talent of Missouri conceded to Democratic challenger Claire McCaskill, who gave a victory speech before the race was called.

"We have heard the voices of Missourians and they have said we want change," McCaskill, teh state auditor, told supporters. "Missourians have rejected the politics of personal character attacks. And they have embraced the power of problem solving and new ideas. The nation was watching, and we showed them."

Democrats need to capture six seats for a majority in the Senate.

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In Virginia, the extremely tight race between incumbent GOP Sen. George Allen and Democratic challenger Jim Webb continued through the night as local registrars counted late reporting precincts.

Webb had a lead of about 8,000 votes over Allen early Wednesday, but vote counting -- and a requested recount -- was expected. None of that stopped Webb from declaring victory before his supporters late Wednesday night. Allen refused to concede anything.

Meanwhile, Republicans acknowledged that three lost seats — in Pennsylvania, Ohio and Rhode Island — indicates voters are frustrated with the war in Iraq.

In Pennsylvania, incumbent Sen. Rick Santorum lost to Democrat Bob Casey after Santorum trailed badly in the polls for months. In Ohio, Democratic Rep. Sherrod Brown beat Republican Sen. Mike DeWine in a state that has been rocked by scandal and saw turnovers in the governor's seat.

Early on, Republican Sen. Lincoln Chafee had distanced himself from President Bush and conservatives in his party, but he couldn't hold out against Democrat Sheldon Whitehouse.

"We have to roll up our sleeves and get to work on the business of changing our country," said Casey in his victory speech.

And in Maryland, Democratic Rep. Ben Cardin beat back a tough challenge from Republican Lt. Gov. Michael Steele, keeping that seat in Democratic hands after Sen. Paul Sarbanes' retirement. Steele refused to concede until Wednesday morning.

In Tennessee, Republican Bob Corker defeated Democratic Rep. Harold Ford Jr. following a hotly contested campaign.

Republicans did not fare as well in New Jersey, where the son of a popular governor was not able to defeat the embattled incumbent.

"Tonight, we have chosen here to turn our nation in a new and different course," said Sen. Robert Menendez, who was re-elected after a tough race with Republican opponent Tom Kean Jr. Menendez has been the subject of a Justice Department investigation, while Kean is the son of former New Jersey Gov. Thomas Kean.

Republicans were braced for bad news as exit polls across the country revealed low approval ratings for President Bush, frustration with the war, numerous Republican incumbents set to lose seats in the House and the country's governorships shifting to a Democratic majority for the first time since 1994.

Sen. John McCain, R-Ariz., told FOX News that Republicans will be taking away many lessons from Tuesday's elections.

"We have a strong philosophy that works — we just need to get back to it," he said. "All of us Republicans are going to sit down and listen to the voters and get the message from tonight."

Some seats that were closely watched but didn't change hands included those held by Arizona Republican Jon Kyl and Connecticut Democrat Joe Lieberman.

Lieberman ran for a fourth term as an independent after he was beat in the primary by anti-war Democrat Ned Lamont. But Lieberman won handily and said the night was confirmation of his longtime support in the state.

"My name was on the bottom of the ballot," the 2000 Democratic vice presidential candidate told supporters Tuesday night. "So it seems only fitting that I thank you from the bottom of my heart. And I promise you that I will do everything I can as your United States senator to make the most (of) the great honor and opportunities you have given me today."

Vermont's Bernie Sanders, a longtime independent representative in the House, was elected to replace retiring independent Sen. Jim Jeffords from the same state.