With six Democratic candidates still in the field and more than 90 percent of the delegates yet to be chosen, The New Republic has endorsed Tennessee Sen. Albert Gore Jr. for president and promised him its support "against any likely or imaginable Republican opponent in November."

The endorsement, published in the March 7 issue due on the newsstands Monday, was written by the magazine's owner, editor in chief and chairman, Martin Peretz.

Peretz has been raising money for the campaign and, along with the magazine's literary editor, Leon Wieseltier, advising Gore informally.

Peretz explained the early timing of the endorsement, two weeks before the 20 primaries and caucuses of Super Tuesday, as an effort to "weigh in when it's crucial for him."

The New Republic habitually endorses presidential candidates -- Democrat Walter Mondale in 1984, independent John Anderson in 1980, Democrat Jimmy Carter in 1976 -- but typically the magazine announces its choice in the fall, just before the general election.

Unlike those qualified and tepid endorsements, this year's "Our Choice" editorial, accompanied by a statesmanlike cover portrait and the slogan "Al Gore for President," is a hymn of praise to the 39-year-old freshman senator.

In a brief disclaimer elsewhere in the issue -- "just to stave off the conflict-of-interest fetishists" -- the magazine acknowledges that Gore is "a friend of several editors of this journal and a former student of the editor-in-chief." As a member of the Harvard University faculty, Peretz first met Gore when he was an undergraduate 22 years ago.

Peretz said yesterday that during Gore's presidential campaign, "I've spoken to Al a decent amount" to provide informal advice and offer direction, but "I'm outside the campaign."

The editorial begins by disposing of Rep. Richard Gephardt (for his "crude populism of unwarranted grievance and unwarranted resentments") and Massachusetts Gov. Michael Dukakis (for a "rigidity {that} derives from no great passion for ideas, no deep convictions about issues") and then lays out the case for Gore.

It praises his "complexity of mind," his "grasp of what our future economy needs to look like," his "near-legendary ability to grasp the meaning of new and adventurous technologies" and his "mastery" of arms-control issues.

Addressing the issue of Gore's privileged background as the son of a senator, the editorial states: "The point is not, as 'Doonesbury' seems to think, that Gore believes he was born to govern. The point is that he wants to serve. In that sense, he is quite old-fashioned. He thinks of America as one people and not as atomized individuals."

The New Republic's history, Peretz said, "is of being deeply involved in the politics of the country. Imagine setting limits to who Walter Lippmann could talk to. It's preposterous." (Lippmann, while writing for The New Republic and other publications, informally advised presidential campaigns and incumbent presidents.) "Some readers will disagree, of course," Peretz added, "but no one will feel we're doing something out of line, that we can't be trusted."

He described his relationship to the Gore campaign in a series of negatives: "I've never been to any organizational meetings, I've never been in the headquarters, I've never sat down and had a strategy meeting with any staff person."

According to Federal Election Commission records, Peretz, his wife and two children each have contributed $1,000, the maximum allowable, to the Gore campaign.

Wieseltier described himself as the principal person from The New Republic, other than Peretz, advising the Gore campaign.

"I've been helping him with speeches, with political strategy, with a discussion of ideas. Al's a pretty reflective man, so we talk," Wieseltier said. "This is the occupational hazard of political intellectuals in Washington. I like to think our readers will treat us not just as insiders but as honest men and women."

Not everyone in the magazine's editorial councils was in agreement with the endorsement of Gore. Michael Kinsley, the magazine's editor, said, "I'm a citizen of Maryland and I'm voting for Dukakis on Super Tuesday ... But I will vote for Gore with pleasure if he gets the nomination."

Despite his personal preference for another candidate, Kinsley said, "I like the idea of The New Republic endorsing someone in the primaries."

And echoing Peretz, he said, "We have no problem with anyone being engage' in any way they wish. It's one of the privileges of working at a journal of opinion as opposed to a newspaper. It would curdle your ombudsman."