July 15, 1984

The New Zealand Labor Party swept Sir Robert Muldoon's conservative National Party from power in general elections Saturday, a result that American officials say could cause major problems for United States military commitments in the region. Although New Zealand political observers and officials said the chief issues in the election were domestic, the Labor Party has called for a rene gotiation of the country's 33-year-old defense treaty with the United States and Australia. It also wants to ban American nuclear-armed and nuclear- powered naval vessels from New Zealand waters. Latest reports from the New Zealand radio gave the Labor Party, led by David Lange, a 41-year-old lawyer, a 17-seat margin over Sir Robert's party, which has been in power for nine years. The projections broadcast by the New Zealand radio gave the Labor Party 55 seats in the new Parliament and the National Party 38, with 2 seats going to the Social Credit Party.

PRESIDENT REAGAN was point man again last week, but the whole team was playing in the White House campaign to present the Administration's record as progress and its critics as carping. In a three-day series of events his re-election advisers acknowledged was designed to deflect attacks on his environmental policies, the President traveled to the polluted Chesapeake Bay to publicize his $10 million cleanup program for it, to Theodore Roosevelt Island in the Potomac River to sign the 14th annual Environmental quality Report and to pledge efforts to preserve endangered species and protect wilderness lands, and to Mammoth Cave National Park in Kentucky to tell 15,000 members of the National Hikers and Campers Association that cleanup efforts generally had lost ''some of their energy and direction'' until he came to Washington. The hikers and campers received his remarks well. Environmental groups had been irritated all week. William Butler, vice president for government relations of the National Audubon Society, among others, noted that the budget of the Council on Environmental Quality has been cut by two-thirds since 1980; other Federal environmental programs have also fared poorly.

- Donna Horton White, who underwent back surgery less than a year ago, tied Amy Alcott for the lead after three rounds of the 39th United States Women's Open at the Salem Country Club today. The 30-year-old Mrs. White, who has not won a major in her three professional victories, shot par 72 for a 54-hole total of 2-over-par 218. Miss Alcott, the 1980 Open champion, who had two spectacular 5 iron approach shots today, scored 73 for her 218. The final round of the $225,000 Ladies Professional Golf Association tournament is scheduled for Sunday.

The United States put a spirited end to the bitter memories of last year's early-round elimination by Argentina in Davis Cup competition, as John McEnroe and Peter Fleming defeated Jose- Luis Clerc and Martin Jaite in doubles today to clinch the three-of-five- match quarterfinal series, 3-0. The scores of the match, which had many verbal outburts from both sides and a face-to-face confrontation between McEnroe and Clerc in the third and most volatile set, were 7-5, 4-6, 6-3, 6-1. With the victory, the Americans moved into the semifinals against the Australia-Italy winner. That series in Brisbane, Australia, was postponed by rain.

There has been no down-shifting in sales of heavy trucks, which are near the record set in October 1979 - and may even break it before the year is out. ''Class 8'' trucks, which have a combined vehicle and cargo weight of 16.5 tons, represent a costly investment to even the biggest motor carriers.