MANCHESTER, N.H. -- Here's what to watch for when the returns come in on the New Hampshire presidential primary tonight:
On the Republican side, there is only one number that matters -- the share of the vote for conservative commentator Patrick J. Buchanan. On the Democratic side, the critical question is likely to be who finishes third and with how many votes.
The Republican calculus works this way: If Mr. Buchanan wins 35 percent or more, the results will be read as a slap at President Bush. If the Buchanan vote exceeds 40 percent, the White House will be severely enough embarrassed to set off a round of serious hand-wringing and demands for a new strategy.
On the other hand, if Mr. Bush wins 60 percent or more and holds Mr. Buchanan under 35 percent, the Bush campaign will be able to dismiss the challenge as more of a nuisance than a serious threat. And Mr. Buchanan will find it far more difficult to raise the money to continue.
On the face of it, it may seem precious to put so much stress on a few percentage points. But politics is a business of perceptions and atmospherics, and a weak showing by Mr. Bush will be taken within the political community as a warning sign of serious potential distress later in the year.
In the last similar case of a party maverick challenging a sitting Republican president, Rep. Paul N. McCloskey polled 19.8 percent and Rep. John Ashbrook 9.7 percent against President Richard M. Nixon in 1972. Mr. McCloskey's challenge was spurred by his opposition to the Nixon policy on the war in Vietnam and attracted both liberal-to-moderate Republicans and a substantial bloc of independents.
On the Democratic side, the attention to who finishes third rests on the assumption that former Sen. Paul E. Tsongas of Massachusetts and Gov. Bill Clinton of Arkansas confirm the expectations raised by opinion polls and finish first and second.
Because of their doubts about the long-term viability of either Mr. Tsongas or Mr. Clinton, the Democrats will be looking for some sign of life from a candidate who might be considered a realistic alternative.
That means that if either Sen. Bob Kerrey of Nebraska or Sen. Tom Harkin of Iowa finishes with a respectable 18 percent to 19 percent of the vote and a lead of at least 5 percent over the other, he will be positioned to establish himself as a serious competitor by making a stronger showing in coming primaries in South Dakota next week and some of the seven primaries and caucuses scheduled March 3.
This formulation applies more to Mr. Kerrey than to Mr. Harkin, however, because of continuing doubts about whether the Iowan's old-fashioned liberal rhetoric is a marketable commodity in the general election. Because of his record as a war hero, Mr. Kerrey is considered likely to be far more acceptable to culturally conservative southern Democrats who have been deserting the party in droves for both Ronald Reagan and Mr. Bush in the last three elections.
The question of whether a third Democrat, other than Mr. Tsongas and Mr. Clinton, survives New Hampshire is important in the eyes of Democratic professionals because of how it could affect the shape of the party field later. The rough consensus among Democratic professionals who have gathered here in droves is that if the choice appears to be between Mr. Tsongas and Mr. Clinton, there may be a late entry such as House Majority Leader Richard A. Gephardt of Missouri.
The other potentially important variable in the Democratic returns is the showing of the movement to write in the name of Gov. Mario M. Cuomo of New York. If Mr. Cuomo polls 10 percent to 15 percent of the vote, it will be taken as evidence of both support for him and uneasiness about the choices now being offered, but hardly as proof of an irresistible grass-roots demand for Mr. Cuomo. Anything over 15 percent, particularly if it placed Mr. Cuomo ahead of Mr. Kerrey or Mr. Harkin, would give the draft-Cuomo movement far greater credibility in later primaries.
There is, of course, always the possibility of the kind of upset that, by definition, cannot be foreseen. If, for example, Mr. Tsongas were to lose after leading the polls here for a week, he would be written off as an ephemeral phenomenon who would find it difficult to continue down the road.
If Mr. Clinton wins after all, it will be taken as an extraordinary vindication that defies the conventional wisdom. But a third-place finish would be curtains for his campaign.