The political eruption that has hit the state of New Hampshire this fall has yet to arrive in Iowa. Despite their problems elsewhere, Texas Gov. George W. Bush and Vice President Gore remain the favorites to win next month's Iowa caucuses, the opening round of the 2000 presidential race.

But the question is whether either Bush or Gore will do well enough in those caucuses to boost their prospects in New Hampshire, where they face potentially crucial contests against Arizona Sen. John McCain (R) and former New Jersey senator Bill Bradley (D).

Bradley, who plans a massive television advertising blitz in Iowa next month, hopes to embarrass the vice president in this state, either by holding down Gore's victory margin or springing what would be seen as a major upset to boost his effort to defeat Gore in New Hampshire.

Bush faces possible embarrassment from a well-organized Steve Forbes, whose candidacy will rise or fall based on his performance in Iowa, or a surprise turnout for McCain, who has declined to organize the state but who will be participating in two Iowa debates before the Jan. 24 caucuses.

The first of those debates will be held Monday night in Des Moines, when the six Republican candidates share a stage for the third time in less than two weeks. Republicans in Iowa say the debate may start to bring enthusiasm and intensity to a GOP contest that has been relatively quiet since the frenzy of last August's straw poll.

The debate also presents Bush with an opportunity to snuff out the doubts about his candidacy that have arisen because of what even some supporters see as lackluster performances in the two previous candidate forums.

Iowa already had played its traditional role in the nominating process, which is to winnow the field of candidates. Instead of a dozen Republicans, just six remain, the others victims of the August straw poll and Bush's huge campaign war chest.

But the challenge for Bush is to come out of the caucuses with the kind of impressive showing that the early stages of his candidacy promised. In recent polls, Bush has been close to 50 percent, but he may have trouble living up to those numbers in the precinct caucuses.

No Republican has gotten more than 37 percent of the vote in past caucuses. Bush hopes to break that record. "The object is to come out first, win the delegates and hopefully exceed the record," a senior Bush adviser said.

To reach that goal, Bush is pouring resources into the state, although the campaign's biggest worry now is New Hampshire. Republicans say Bush has the most extensive organization in the state, but in the absence of a dramatic surge by Forbes, Bush officials say their biggest challenge is to keep the troops motivated for another six weeks.

"If it's there, nobody sees it yet," Eric Woolson, Bush's Iowa press secretary, said of a strong challenge from Forbes. "It's hard to keep our people motivated, keeping that sense of urgency."

The candidate with the most to lose in Iowa could be Forbes. He finished second to Bush in the Iowa straw poll and hoped to declare the caucuses a two-man race. Instead, McCain's surge in New Hampshire has drawn attention from his candidacy.

Forbes has concentrated his efforts in Iowa since the straw poll, drawing good-sized crowds on recent visits. He has begun to attack Bush on the abortion issue, bought a half-hour of live television Saturday night and hopes to finish a close second.

At the straw poll, Forbes finished 10 percentage points behind Bush. "Our goal is certainly to get closer," said Steve Grubbs, one of Forbes's Iowa organizers.

But Forbes faces competition from Gary Bauer and Alan Keyes in his bid to win support from Christian conservatives. Bauer has spent considerable time organizing in the churches of Iowa, and the Forbes camp takes his candidacy seriously. Keyes got 7 percent of the vote in 1996 and still enjoys a following in a state where religious conservatives play a significant role in the GOP caucuses.

McCain remains the mystery in Iowa. A new poll shows McCain in third place but still in single digits and well behind Bush and Forbes. Marlys Popma, a veteran organizer who is working for Bauer, said she finds it hard to imagine a candidate without an organization getting any significant vote in caucuses, which require more effort from voters than primaries.

Other campaigns say they have heard reports that Brian Kennedy, former Iowa GOP chairman and a McCain staffer, has been calling into Iowa to stoke support. McCain spokesman Dan Schnur said those calls came before there was a definitive decision not to compete.

"There's been no effort on his or the campaign's part to organize there," Schnur said.

The Democratic fight is more intense, potentially more competitive and Gore's to lose. "The most important aspect [of Iowa] is organization, and Gore has got the edge on that," said Iowa Democratic Chairman Rob Tully. "They're just better organized."

Tully said, however, that Iowa Democrats have become increasingly comfortable with Bradley. "He's starting to catch on with people. The question is whether the campaign is as good as the candidate."

Both campaigns report a high number of undecided Democratic voters, which should worry the vice president more than Bradley. "It would worry me if we didn't have the mechanism in place to take care of it," said Gore's state director Steve Hildebrand.

Bradley appears to hope his January advertising blitz will generate enthusiasm and attract voters who don't regularly attend caucuses. Other campaigns estimate that TV buy at an impressive $800,000, but Bradley's campaign said the figure is lower.

Gore will count on his own organization, the muscle of organized labor and surrogates such as House Minority Leader Richard A. Gephardt (D-Mo.) and members of the Clinton Cabinet to turn out their voters--a prospect that Bradley's campaign thinks about constantly.

"Every time I look out at the horizon, I see the dust from the tanks," said Bradley's state coordinator Dan Lucas. "Because I know they're coming."

CAPTION: Al Gore's campaign in Iowa faces an ad blitz from rival Bill Bradley, but is considered to be better organized.

CAPTION: George W. Bush will debate again tonight in Iowa, where he hopes for a record share of caucus votes.