The polling service that humiliated the television networks on Election Day two years ago suffered a meltdown yesterday, depriving news organizations of the crucial data used to project winners and analyze voting patterns.

Voter News Service, a consortium of the major networks and the Associated Press, pulled the plug on its exit polls after concluding that its computer analysis could not be trusted. The result was to greatly slow the usual drumbeat of television projections in a midterm election filled with tight races.

"It's a very big disappointment," said Ted Savaglio, VNS's executive director. "We have been testing a new system over the last several months. We still were not satisfied with the results of our testing. We very much wanted to provide both state polls and national polls."

Was the multimillion-dollar effort to revamp the computer system a failure? "I wouldn't like to use that word," Savaglio said.

VNS was under intense pressure from its members to avoid a repeat of the debacle during the 2000 presidential election, when the networks used its data to project first Al Gore and then George W. Bush the winner in Florida before pulling back in the middle of the night and declaring the contest too close to call.

Network executives tried to put the best face on the situation last night, saying they would use Associated Press exit polls and other information to try to offset the loss of the VNS data. The consortium was providing only raw vote totals.

"We all like to have winners," said Marty Ryan, executive producer of political programming at Fox News. "We all obsess about who won. In the old days, we would have called at least half the 15 races when the polls close at 8 o'clock."

Ryan said Fox would rely on telephone surveys done for the network yesterday in 10 states, but that such information was not reliable enough to project winning candidates. "There are no secrets between us and our viewers," he said.

CNN political director Tom Hannon said the networks understood that the new system might not work until 2004.

"It does hamper us a little bit," Hannon said. "We're going back to the way we did in the '70s, with old-fashioned political reporting. The only entirely bad thing would be not to be up front and be wrong, two years after Florida."

"Obviously," said ABC spokesman Jeffrey Schneider, "the lack of exit-poll data is not great. But it's not an overwhelming issue for us." He said ABC never planned to do more than suggest "likely" winners, and that "accuracy trumps speed and being first."

MSNBC spokeswoman Cheryl Daly said her network was relying on NBC telephone surveys, dubbed "entrance polls," taken Saturday through Monday. CBS spokeswoman Sandy Genelius said that "VNS was always going to be one tool" in the network's analysis.

By 10:30 p.m., the networks had called just one of the 10 most contested Senate races -- Elizabeth Dole's victory in North Carolina -- and only CBS had projected that Republicans would retain control of the House.

Despite a series of warning signs during test runs in recent days, VNS held out hope that it would be able to provide its clients, including such newspapers as The Washington Post, with at least some of the traditional poll data based on questioning of voters as they left the polls.

Two years ago, a VNS investigation found that the group had underestimated by half the number of absentee ballots in Florida and had dramatically underestimated the number of votes still uncounted at 2 a.m.

Savaglio said there was no problem with VNS's exit interviews in 44 states but that the new software could not adequately process the data. "We chose to keep working right up to the last minute," he said. "We just were not able to feel we had enough confidence. The project to replace the systems top to bottom after 2000 was always a four-year plan."

The networks were largely unable to offer the usual breakdowns of how people voted by age, sex, education, income and political views. By 8 p.m. last night, they had projected as winners eight Senate incumbents whose reelection had never been in doubt.

CBS projected at 10 p.m. that the Republicans would hold the House, but it was not until nearly midnight the network anchors began suggesting that the GOP would likely take over the Senate.

Howard Kurtz is the host of CNN's weekly media program.