One of the surest signs that a presidential campaign was truly beginning was the candidates' courting of William Loeb, who was the irascible right-wing publisher of the Manchester, N.H., Union Leader, the dominant newspaper in the first primary state.

Loeb is dead, but the courting continues.

On Dec. 11, a group calling itself Project '88: Americans for the Reagan Agenda will host a tribute to his memory here.

The guest of honor will be Nackey Loeb, William Loeb's widow and now the publisher. Sponsors say about 1,000 people are expected to attend this political rite, whose significance may be gauged by the keynote speaker: Vice President Bush, a potential 1988 presidential candidate.

The cochairpersons for the evening include Rep. Jack Kemp (R-N.Y.), another possible contender; Senate Majority Leader Robert J. Dole (R-Kan.), also mentioned for the presidential run; Sen. Jesse Helms (R-N.C.); former U.N. ambassador Jeane J. Kirkpatrick; former secretary of transportation Drew Lewis, and the current secretary of that department, Elizabeth Hanford Dole.

Project '88, chaired by the former CIA deputy director Max Hugel, claims a membership of Republican activists who have pledged to remain uncommitted in the presidential race.

By avoiding an early endorsement, they hope to have a greater influence when they finally enter the fray.

Even staying aloof, in presidential politics, is becoming expensive. Attendees at the Loeb event will pay $250. A VIP reception carries a $1,000 price tag.