New Hampshire's presidential primary will be run under different rules in 1980 than in previous years.

The State law still sets the date as "one week earlier than the earliest primary in any other state." With Alabama, Massachusetts, Connecticut and Vermont now scheduled on March 4, 1980, New Hampshire's date would be Feb. 26.

According to Secretary of State William Gardner, these are the key changes in the new election laws.

Procedures have been changed to make it easier to register new voters and to reregister old voters in a different party during the early preprimary period, but not in the few weeks immediately preceding the vote.

Instead of electing delegates separately from the presidential preference or "beauty contest" portion of the ballot on primary day, only the presidential candidates' names will appear on the ballot. Any candidate receiving 10 percent or more of the votes will receive his or her proportional share of the delegates. Lesser percentages will be added to the winner's share.

Each candidate will form his own delegate slate before the primary, designating them in order of preference. Those delegates can campaign for their candidate, but their names will not appear on the ballot.

The expected effect.Gardner said, will be to diminish the impact of wellknown delegate candidates and make New Hampshire's primary a purer presidential preference test. He also said that many observers think the proportional representation feature will encourage more candidates to enter the race.