he battle for control of the US Congress went deep into the night yesterday, with Democrats led by Hillary Rodham Clinton claiming victory in several hard-fought Senate contests, but Republicans believing they had secured the chamber by winning Democratic seats in Virginia and Nevada.
By midnight, ABC and NBC had predicted that the Democrats' campaign to regain the Senate would fall short.
Nor, as the returns trickled in from the East and Midwest, did it appear that the current Republican majority in the House was immediately threatened.
Needing a five-seat pickup to take outright control of the Senate, Democrats scored wins in Delaware, New Jersey, Florida, Minnesota, and New York, where Mrs. Clinton won a historic race.
But the Democrats failed to hang on to a key seat in Virginia, where Senator Charles S. Robb was defeated by former governor George Allen. And in Nevada, former GOP representative John Ensign won a seat formerly held by the Democrats.
House incumbents, as expected, were reelected in large numbers and anxiously awaited the results of closer races that could decide the majority. The Senate races were emotional contests that served as forums for partisan resentment.
In Delaware, Democratic Governor Tom Carper upended incumbent Senator William V. Roth. Roth, 79, had fainted in public during the campaign, raising questions about his age and health.
In Florida, former insurance commissioner Bill Nelson beat Republican Representative Bill McCollum in a race closely monitored by both parties. McCollum, a floor manager during the impeachment of President Clinton, was a particular target.
Mrs. Clinton's win did not improve the Democrats' power base in the Senate, since she will fill the seat being vacating by a Democrat, retiring Senator Daniel Patrick Moynihan. But her victory carried emotional meaning for her party, which managed to keep a Clinton in office.
And in Missouri, sitting Senator John Ashcroft was fighting to hang on to his seat in a campaign against Democrat Mel Carnahan, the state's late governor.
Jon Corzine kept the open New Jersey Senate seat in the Democratic column, besting Republican Representative Bob Franks and spending an astounding $55 million of his own money to do it.
In Minnesota, Democratic challenger Mark Dayton also found that self-financing paid off: he beat the incumbent, Republican Rod Grams.
Massachusetts, predictably, reelected its congressional incumbents: Senator Edward M. Kennedy and the all-Democratic House delegation.
Republican Senators James Jeffords of Vermont, Lincoln Chafee of Rhode Island, and Olympia Snowe of Maine also were reelected.
In the Senate, the Democrats hoped to make strong enough gains to take control of a chamber where the Republicans outnumber them, 54 to 46.
The fight for control of Congress was the most expensive in history and one of the hardest fought. Many of the issues that dominated the presidential campaign - health care, prescription drug coverage, and tax cuts - played a role in the congressional contests as well.
Money was a driving force in the fight for the majority in both houses of Congress. All told, about $1 billion was spent on House and Senate campaigns. And that total didn't include the unregulated ''soft money'' spent by national party organizations or the independent expenditures of special interest groups, according to the nonpartisan Center for Responsive Politics in Washington, D.C.
''It's definitely going to be a record'' in spending, with two of the Senate races - the New York and New Jersey contests - costing staggering amounts, he said.
And campaigning in the last weeks of the races became negative, even brutal.
Supporters of Republican Representative Rick Lazio left phone messages with voters accusing Mrs. Clinton of being tangentially responsible for the attack on the USS Cole off the coast of Yemen. The negative message was based on the disclosure that Mrs. Clinton had accepted a campaign contribution from a Muslim group, money she later returned.
One end result of the hotly contested congressional campaign was the unappetizing prospect of even greater gridlock.
The narrow margin guarantees that ''no president can accomplish anything'' without at least some support from both parties,'' said Representative Edward J. Markey, Democrat of Malden.
