Vice President Gore won an overwhelming victory in the Democratic caucuses here in Iowa tonight, while Texas Gov. George W. Bush scored a clear but narrower victory over his five Republican challengers.

Gore crushed Bill Bradley with an across-the-board show of strength that left the former New Jersey senator on the defensive and scrambling to avoid a potentially debilitating loss in New Hampshire on Feb. 1. Gore captured 63 percent of the vote, to 35 percent for Bradley.

Gore demonstrated the kind of political muscle a sitting vice president can bring to bear in a contest dominated by party activists. He now hopes to use the momentum from Iowa to cripple Bradley in the state that helped propel Bradley's candidacy and where independent voters play a more significant role.

Bush managed to cement his status as the national frontrunner in the Republican field with a double-digit victory, winning about 41 percent of the vote, the highest percentage ever in a contested GOP caucus in Iowa.

Magazine publisher Steve Forbes finished a clear second to Bush with about 30 percent, while Alan Keyes, the fiery antiabortion activist, provided one of the night's big surprises by finishing third at 14 percent.

Arizona Sen. John McCain, who has staked his candidacy on primary contests in New Hampshire and South Carolina, did not campaign here actively and finished fifth behind Gary Bauer, the former head of the Family Research Council. Bauer won about 9 percent to McCain's 5 percent. Utah Sen. Orrin G. Hatch lagged behind his opponents to finish last with 1 percent and has scheduled a news conference in Washington for Tuesday amid speculation that he will quit the race. Bauer may feel a similar pressure.

Forbes's showing here, which was significantly better than the final pre-caucus polls had predicted, adds an element of uncertainty to the Republican contest in New Hampshire and potential trouble for Bush.

Until tonight, Bush's main challenge in New Hampshire and in national polls was McCain, who has challenged the Texas governor from the left. Bush now faces a potential challenge as well from the right by Forbes, who enjoys the endorsement of the conservative Manchester Union Leader.

Tonight's caucuses marked the first official contests of the 2000 presidential campaign and are just the opening round of a process that will culminate at the Democratic and Republican national conventions in the summer, when the two parties formally choose their nominees.

Not since Jimmy Carter in 1976 has the winner of a contested caucus fight in Iowa gone on to win in New Hampshire, but advisers to Gore and Bush believe they are now in position to do so. Victories there would put them in a commanding position to win the nomination.

An ebullient Bush hailed what he called a "record-shattering victory" and said the results mark "the beginning of the end of the Clinton era." Before cheering supporters at a downtown hotel, Bush said he had proved he can unite the Republican Party, emphasized his conservative credentials and began to reach out to all voters.

"If you are tired of the bitterness that poisons our politics, come join us," Bush said. "If you think that government should be less partisan and more practical, come join us. If you are weary of polls and posturing, of scandals and alibis, come join us."

But Forbes said he was "very elated, very excited, very happy" about the results, calling the results "a great victory of ideas and conservative principles."

Saying the race in New Hampshire pits "a conservative against two moderates," Forbes added in an interview tonight that the caucuses provided "an enormous boost. I think we've got a very dramatic three-way race now."

As the votes were being counted in Iowa, McCain told a spirited rally at Dartmouth College in Hanover, N.H., "The preliminaries are over; the playoffs begin tomorrow and we're going to win that playoff."

McCain, who said he had no regrets about not competing in Iowa, predicted "a history-making seven days" between now and the New Hampshire primary, telling his supporters, "A week from tomorrow we can make American political history. We can surprise them all--the inside-the-Beltway gasbags who said we didn't have a chance. We can show them."

Keyes, who had a strong following among religious conservatives in this state, said, "I think as time goes by, more Americans are going to realize that the real purpose is to vote our conscience and vote our hearts. . . . We will continue to do what we have done."

As various Republicans claimed a boost from their showings, there was no ambiguity about the Democratic contest. The night belonged clearly to Gore. But he vowed no let-up in New Hampshire, where he predicted an "arduous" week of campaigning against Bradley. "My message to you this evening is very simple," he told about 800 supporters at the Iowa fairgrounds. "We've just begun to fight."

Gore praised Bradley as "a good person and a tough competitor" but said his opponent was wrong to ask if the country is better off now than seven years ago. "The answer is clearly yes," he said. "The question is can we do even better. I believe the answer is yes and I ask you to join with me to fight for a better future."

Bradley, addressing his own supporters, congratulated Gore on a "strong showing" in Iowa and made reference to the toughness of his Democratic rival. But he said he was ready for the next round in New Hampshire and beyond. "I've always said that running for president is a mixture of humility and confidence . . . " Bradley said. "Tonight I have a little more humility but no less confidence that I can win and do the job."

Gore's victory was especially sweet after a 1999 dominated by news about his weaknesses as a candidate and turmoil within his campaign. Despite Gore's institutional strength, Bradley appeared to be gaining strength in Iowa throughout the summer and early fall. But two events helped blunt his rise, according to Democrats in the state.

The first came at a Democratic dinner in October, where Gore delivered an impassioned speech and criticized Bradley for refusing to "stay and fight" the Republicans who controlled Congress. Bradley quit the Senate in 1996. The second turning point came on Jan. 8, when the two Democrats debated in Des Moines. Gore put Bradley on the defensive over agriculture policy and never stopped applying the pressure to his rival.

Entrance polls tonight showed Gore winning virtually every category of Democratic voter. Men and women voted for him in roughly equal percentages, as did liberals, moderates and conservative Democrats. The only demographic group that went to Bradley were voters with incomes of more than $75,000.

Gore took more than two-thirds of the votes in union households but also won a clear majority of those in non-union households.

The Democratic results also underscored the help Gore is receiving in the nomination fight from his service as President Clinton's vice president, whatever his association with Clinton may mean if he becomes the Democratic nominee. Clinton tonight offered his congratulations by telephone from the White House.

Gore won roughly two-thirds of the Democratic voters who approve of Clinton's job performance, while Bradley captured the votes of those who disapprove. But those who approve dominated the caucuses, accounting for more than four in five Democratic voters.

Democratic caucus-goers overwhelming saw Gore as the stronger leader, the candidate with the most experience and the Democrat who can win in November. Bradley was seen as the candidate with new ideas. Democrats also judged Gore superior on the issues they cared most about: health care, taxes, the economy and even campaign finance reform.

Gore overwhelmingly won Democrats, who dominated the caucuses, while he and Bradley roughly split the relatively few independents who participated.

In the GOP caucuses, Bush demonstrated strength across the board, winning a plurality among men and women, among every age group and among conservative, moderate and liberal Republicans. Bush ran strong among older voters and among voters with incomes of more than $75,000. He also won among religious conservatives, despite criticism from his rivals that he doesn't care about social and moral issues.

Forbes was seen as stronger than Bush on the issues of taxes and abortion and as a candidate who stands up for what he believes in. Voters who cited moral values rated Forbes stronger than Bush, with Keyes a close third.

Bush was judged by Republican caucus-goers as a stronger and more experienced leader, and on the question of who can win in November, he was an almost unanimous choice.

Tonight's voting took place at more than 4,200 meetings in churches, schools, firehouses and living rooms throughout the state, with Republicans voting by secret ballot and Democrats engaging in a more arcane and public process to determine the strength of each candidate.

Iowans jealously guard their status as the state with the first caucuses. Kayne Robinson, the Iowa Republican chairman, said the process here puts special demands on candidates and gives voters here a unique, up-close view that voters in other, larger states do not get. "We scald them like a chicken and take the feathers off," he said this morning at the Drake University arena that served as the GOP tabulation center. "It's pretty hard to be a phony after 20 or 30 visits."

The caucuses represented a test of organizational strength of the two Democrats and six Republicans. In contrast to presidential primaries, the caucuses require voters to commit several hours of their time at meetings where they not only express their presidential preferences but also debate and discuss party issues.

Staff writers Mike Allen, Ceci Connolly, Terry M. Neal and Ben White contributed to this report.

Iowa Vote

Here are the latest unofficial returns from the Iowa caucuses.

REPUBLICANS

95% of precincts reporting

Bush 41%

Forbes 30%

Keyes 14%

Bauer 9%

McCain 5%

Hatch 1%

DEMOCRATS

98% of precincts reporting

Gore 63%

Bradley 35%

SOURCE: Associated Press