In the battle for Maryland's open Senate seat, Democrat Ben Cardin, a U.S. Representative, was the projected winner over Republican Michael Steele.
CBS News estimates that in Ohio, seven-term Democratic Rep. Sherrod Brown has won over GOP Sen. Mike DeWine. The last time a Democrat won a Senate race in Ohio was 1992. Brown won among voters of both genders, all age groups and all races in the state.
In Pennsylvania, CBS News estimates GOP Sen. Rick Santorum — the third-ranking Republican in the Senate — was defeated by his pro-life Democratic opponent, State Treasurer Robert Casey Jr., the son of a popular former governor.
Among Democratic incumbents, only Menendez was considered in any real danger. But until the end, he held a 48-43 percent edge over Republican challenger Tom Kean Jr., and came out on top, according to projections.
Sen. Joe Lieberman is projected to have narrowly averted the threat to his seat from cable executive Ned Lamont, who won Connecticut's Democratic primary and caused the one-time presidential candidate to run on a third-party ticket.
But as polls continue to close around the nation, a series of cliffhangers stacked up as the contentious Senate races in Virginia, Tennessee, Maryland, Missouri and Rhode Island were determined to be.
Meanwhile, Democratic Sen. Robert Byrd retained his seat in West Virginia, and the first returns of the night made Rep. Bernie Sanders, an independent, a winner in the Vermont Senate race, succeeding retiring Sen. James Jeffords. Brooklyn-born with an accent to match, Sanders is an avowed Socialist who will side with Democrats when he is sworn into office in January.
In preliminary exit polls in Virginia, Jim Webb — a best-selling author, Vietnam Marine and former Republican — was just ahead of the incumbent, Sen. George Allen. Once a long shot, Webb has made the race a toss-up. Allen was a presidential contender a year ago, but now he's fighting for his life after a series of campaign gaffes and errors.
Also in Virginia, voters passed an amendment banning same-sex marriage.
The past few months have been an uphill battle for the Democrats, who must gain six seats to make a Senate majority. After significant gains by the Democrats against GOP incumbents this fall, they are knocking on the Senate door.
"The wind is blowing very much for the Democrats, and it looks like a strong wind," said CBS News chief Washington correspondent Bob Schieffer.
Democrats appealed to voter weariness with the war, GOP White House and recent corruption scandals asto fill 33 of the Senate's 100 seats. Democrats need a net pickup of six seats to recapture the majority that they last briefly exercised in 2001-2002. Seventeen seats now held by Democrats and 15 seats now filled by Republicans, including the Tennessee post of retiring Majority Leader Bill Frist, are up for grabs.
Conventional wisdom said the Democrats were well-positioned to pick up seats in Ohio, Rhode Island and Pennsylvania. They were leaning behind in Tennessee, which was a toss-up a week ago. If they lose there and hold all their current seats, Democrats would then need to win all three remaining toss-ups: Virginia, Missouri and Montana.
Meanwhile, Republicans' reign over theTuesday as a surge of Democratic support sparked by voter outrage over the Iraq war and disapproval of President Bush and Congress gave Democrats a chance to regain a majority in the House for the first time since 1994.
Other projected Senate wins include:
Democrats last controlled the Senate in 2002. Republicans now control 55 seats in the 100-member chamber. Two Independents, Sanders and Lieberman, will caucus with the Democrats and count toward Democratic tallies. If there's a 50-50 split in the Senate, Vice President Dick Cheney serves as the tiebreaker, meaning the majority leader and committee chairs would be Republican and any split-down-the-middle votes would be decided by Cheney.
Races to keep watching:
By Christine Lagorio