Nunn's `no' is a blow to Democrat hopes in South. When Sen. Sam Nunn of Georgia said `no' to a White House bid, the Democrats lost what some political experts saw as their strongest chance to capture the South. The other, more liberal Democratic hopefuls hold less appeal to Southern white voters.

After tantalizing the political world for months, Sam Nunn yesterday said ``no'' to a race for the White House. Now the big, worrisome question for Democrats is: What will the South do in 1988?

Senator Nunn's decision took the strongest Southern Democrat out of the running, in the view of most analysts. The Georgian, a classic-conservative Southern politician, is highly regarded, not only by Democrats, but also by many Republicans.

Nunn's name on the ticket might have drawn back millions of disenchanted Southern whites who in recent years have been attracted to the GOP by Ronald Reagan and his conservative themes.

Nunn gave two major reasons: his family and his Senate responsibilities.

Analysts give another reason: Nunn probably could not have won the Democratic nomination anyway. Liberal party activists dominate the Democratic primaries and caucuses.

(Sen. Paul Laxalt bows out of GOP race, Page 6.)

Following in the footsteps of earlier Southern leaders, such as Sen. Richard Russell of Georgia, Nunn is the party's preeminent expert on defense matters. In January, he fulfilled a goal by becoming chairman of the Senate Armed Services Committee.

In a letter to supporters, Nunn explained: ``I know myself pretty well, and I have concluded that if I attempted to run for president, and also carry out my Senate duties, I would wind up doing neither well.''

Nunn, who avoids the Washington social circuit and likes nothing better than a quiet evening at home, also worried about the effects on his family. He has a son in high school and a daughter in college.

Yet the decision greatly disappointed his supporters.

``I was very, very sad to hear that,'' says Rep. Buddy Darden (D) of Georgia. ``I think he would have made an excellent president.''

Many Republicans agree. Barry Goldwater, the GOP's 1964 presidential nominee, said in a recent Monitor interview: ``Nunn's about the best man we have in this country right now.'' Mr. Goldwater said a contest between Nunn and Vice-President George Bush would be a great campaign: ``It would be a good, clean, decent race, and I wouldn't bet on either one, it would be so close.''

The Democrats desperately need Southern votes in 1988. In an effort to court the region, the party leadership has chosen Atlanta for its national convention next summer. They have also attempted to give the South more influence through the Super Tuesday primary next March 8.

Nunn's withdrawal will swing some Southern support in the direction of Sen. Albert Gore Jr. of Tennessee, the youngest candidate in the 1988 campaign.

But Senator Gore comes out of a liberal Tennessee tradition. By labor-union standards, he has an almost perfect voting record. He was educated at a Washington, D.C., prep school and at Harvard and Vanderbilt Universities.

Political analyst Richard Scammon quotes a recent line about Gore: ``He has his feet in Tennessee, and his heart in Berkeley.'' Another analyst, Stephen Hess, says simply: ``Gore is not an unalloyed Southerner.''

Other choices now before the Democrats may fare no better in the South. Most can be categorized as Northern liberals, out of the same school as Walter Mondale and Hubert H. Humphrey.

The current leader appears to be Michael Dukakis, governor of Massachusetts, perhaps the most liberal state in the nation. The field also includes Sen. Paul Simon of Illinois, who boasts of his liberal credentials; Sen. Joseph Biden Jr. of Delaware, with a solidly liberal voting record; former Gov. Bruce Babbitt of Arizona, also considered liberal; Rep. Richard Gephardt of Missouri, with strongly liberal credentials; and the Rev. Jesse Jackson, waging a crusade for minority rights.