It's countdown time in Northeast politics

All that we want is to be first. We are not trying to be a political bellwether.'' That is how Steve Barba, the selectman in tiny, snow-quilted Dixville Notch, views his rural hamlet's role as the ''ribbon cutter'' in the first-in-the-nation presidential primary.

Local citizens - all 27 of them - will gather late next Monday evening, and precisely at midnight they'll cast their paper ballots, stick around while they are counted, and head home. It has been a tradition in the north country outpost 10 miles from the Canadian border in every presidential primary since 1956.

Thus far two of the eight major Democratic candidates - Reubin O. Askew and Ernest F. Hollings - have visited Dixville Notch, where Republicans outnumber Democrats by 18 to 4, with four registered independents.

What the town's vote may lack in impact, it may make up for in foresight, if the 1980 vote is any indication: Dixville Notchers chose Ronald Reagan and Jimmy Carter, the eventual nominees of the two parties. The Reagan victory, however, was far from overwhelming. He edged out George Bush by a single vote.

This time, besides the eight better-known Democratic contenders - Mr. Askew, Senator Hollings, Alan Cranston, John Glenn, Gary Hart, Jesse Hackson, George McGovern, and Walter Mondale - at least a dozen lesser-knowns are on the party's presidential primary ballots in other cities and towns in the Granite State.

On the Republican ballot, President Reagan has four challengers, perhaps the best-known of them being one-time Minnesota Gov. Harold E. Stassen, a perennial White House aspirant.

Unlike the Democratic candidates, who have spent considerable time and effort campaigning in the Granite State, the President has not come here, nor is he expected to. Vice-President Bush, however, was dispatched to New Hampshire last week to serve notice that Mr. Reagan is not taking for granted the voters that handed him his first primary victory four years ago.

Voter-preference polls, including one completed last week for the Boston Globe, indicate a wide New Hampshire lead for Mr. Mondale. None of his Democratic opponents, however, are conceding him the lead - least of all Senator Glenn, who has been runner-up, although a distant second, in the polls.

The extent to which any candidate can cut into the Mondale lead may depend on their performance in a 90-minute debate tonight at St. Anselms College in Manchester, sponsored by the League of Women Voters. Tonight's debate, being carried nationally by network radio and public television, is expected to attract a wider home-viewer audience than any of the previous programs.

So far, the candidates have aimed their attacks mostly at President Reagan rather than each other. There have been few hard-hitting exchanges among them, except in the closing portion of the Jan. 15 televised debate at Dartmouth College, when Glenn went after Mondale, only to be chastised by McGovern.

Glenn forces in New Hampshire view the coming primary with some apprehension, especially in light of the Iowa caucuses, in which the former astronaut finished fifth instead of the expected second behind Mondale. A poor showing here would be all but impossible for Glenn to overcome, observers generally agree.

The Hart candidacy, which has been increasing in momentum in New Hampshire in recent weeks, appears to have been buoyed considerably by his second-place showing in Iowa, well ahead of all other Mondale foes. A strong No. 2 ranking in New Hampshire could Senator Hart the kind of momentum needed for him to emerge as most formidible Mondale challenger.

With the New Hampshire phase of the campaign in its final days, most of the Democratic presidential hopefuls are trekking through the state with increased vigor. Many of them, including candidates Mondale, Glenn, Hart, and Jackson, have enlisted their Massachusetts forces to aid in the crucial push here.

Despite the attention being focused on the Granite State, most of the candidates have been touching political base in at least two neighboring states, Maine and Massachusetts.

After the Feb. 28 primary, Rhode Island will be getting a lot more direct attention. So will Vermont, where Askew, Hart, Jackson, and Mondale are competing in a nonbinding popularity contest on the Green Mountain State's March 6 ballot. The informal poll, however, will not decide the apportionment of Democratic National convention delegates from that state. That will come later in the spring at a party conclave.

Two days later, Maine town caucuses will be held to choose delegates to the state's convention in April. There, based on the strengths of the presidential contenders at the earlier caucuses, some 3,300 Democratic delegates will be selected to attend the national convention this summer.

As important as both the New Hampshire primary and the Maine caucuses are to the candidates, these contests may be overshadowed, at least in terms of delegate seats involved, by the March 13 primaries in Massachusetts and Rhode Island.

About two-thirds of the Bay State's 116 delegates and most of Rhode Island's 27 will be apportioned to candidates based on these primary votes. At issue in the New Hampshire primary are but 22 Democratic national convention seats. Vermont has only 17 chairs to fill, and Maine has 27.

By the time the Connecticut primary rolls around on March 27, a clear-cut leader for the Democratic nomination may have already emerged, political leaders there concede. That could significantly diminish the impact of balloting in the Nutmeg State, where 60 delegates are to be chosen.

Unlike New Hampshire, where any American citizen can get on the primary ballot by paying a $1,000 filing fee, the Democratic primary competition in Massachusetts, Rhode Island, and Connecticut is restricted to the eight major candidates.

On the Republican side, President Reagan will have no challengers on New England ballots, except for in the Granite State, where none of the other GOP aspirants appear formidable. Write-in votes, however, are permitted in Massachusetts as well as New Hampshire.

The endorsement of Mondale by the AFL-CIO and support by activist groups such as the National Organization of Women have boosted the former vice-president's forces throughout the six-state region.

Here in Massachusetts, Mondale's allies include Gov. Michael S. Dukakis, US House Speaker Thomas P. O'Neill Jr., US Rep. Barney Frank, and state House Speaker Thomas W. McGee.

Glenn, on the other hand, has the support of US Sen. Paul E. Tsongas, state Attorney General Francis X. Bellotti, and state Senate President William Bulger.

The latest Boston Globe New Hampshire poll, published Feb. 19, showed that among those Democrats who said they were likely to vote, 36 percent favored Mondale, compared to 16 percent for Glenn, 13 percent for Hart, 10 percent for Jackson, 6 percent for McGovern, 5 percent each for Cranston and Hollings, 3 percent for Askew, and 6 percent undecided.

A similar opinion sampling in mid-December gave Mondale 46 percent to 16 percent for Glenn. Hart was next with 8 percent, then Jackson with 6 percent. There were 12 percent undecided.

The New Hampshire primary comes a week earlier than is permitted under national party rules, and attempts to gain a waiver have been unsuccessful. The problem stems from a state law that requires that the vote in New Hampshire come at least a week before the primary in any other state.

Vermont chose March 6, the day of its town meetings, for its nonbinding contest; thus New Hampshire officials say they had no choice but to schedule its primary on Feb. 28.