There was a sad little press conference the other day announcing the formation of MODRN, a political action committee to support "Moderate Republican Candidates."

Rep. Bill Green (R-N.Y.), who occupies the Manhattan silk stocking district once held by John V. Lindsay, was there, as the sponsor and spokesman for the group. Ex-Rep. Pete McCloskey of California, who challenged Richard Nixon's renomination in 1972, showed up late to lend his support.

Up from Duke University Law School, trailing echoes of the past, came Arthur Larson. As a protege of President Eisenhower in the mid-1950s, he wrote a book called "A Republican Looks at His Party." Larson dutifully read some passages from the book, recalling memories of Eisenhower's dream of a "modern Republicanism," for the edification of the three reporters present.

The advisory committee of the new fund includes names like Pillsbury, Seymour, Rockefeller and Rothschild--a reminder of the day when vast amounts of money and political influence were wielded by the eastern establishment of the GOP. But Green set no financial goals for the new organization, and his expectations are deservedly modest.

A similar group, chartered by the liberal Republican Ripon Society, raised only $9,640 in the 1981-82 election cycle.

Theoretically, one can argue that even in the era of Ronald Reagan, the moderates retain enough leverage to have some role in drafting the Republican platform of 1984 and even influencing the shape of Reagan's possible second term.

The swing block in the United States Senate is composed of moderate Republicans. Where the four D's--Dole, Domenici, Danforth and Durenberger--go, is usually where the Senate goes, especially on issues of fiscal and budget policy and taxes. Robert Michel, the Republican leader of the House, is a man of similar moderate character and outlook.

The governors of most of the states now in Republican hands, including political heavyweights from Pennsylvania, Delaware, Illinois, Vermont, and Tennessee, are also in that progressive tradition.

There is evidence in some of the polls that one of the key voting groups in the 1984 electorate may be the moderate Republicans. A study by Robert Teeter for the Republican Congressional Campaign Committee showed heavy swings against the Republicans from 1980 to 1982, among those who call themselves Independent or "leaning Republican" voters. There were similar swings of 10 to 12 points among those with incomes over $30,000 and those with college educations--the profile of the moderates.

Getting those voters back in the Republican column is important not only to Ronald Reagan but to continued Republican control of the Senate. But as things stand, the moderates will exert almost no influence on their party's future direction. They may grumble, but they will take whatever Reagan hands down as party doctrine.

Sen. Bob Packwood of Oregon, who embodies the progressive tradition, is traveling the country warning that Reagan's views on the environment, civil rights, women's rights and labor issues are jeopardizing constituencies of vital importance to the Republican Party's future. But Packwood says he will not challenge Reagan, so his criticisms are easily ignored.

A couple dozen Republican men and women, some prominent in past administrations, some in office now, have met intermittently to discuss an agenda for 1984 and beyond, but they have settled on no strategy. If you ask why this impotence, you get two answers. One is that the most prestigious potential spokesman for moderation--retiring Senate Majority Leader Howard H. Baker Jr. of Tennessee--has his own political fish to fry. He wants to remain in Reagan's good graces and he wants to avoid making him an enemy in the 1988 presidential nomination fight.

Second, one is told, there is the curse of Nelson Rockefeller's legacy. In times when moderates were dominant in the GOP, conservatives felt free to press their demands on the party. Sen. Jesse Helms (R-N.C.), for example, insisted on rewriting Jerry Ford's foreign policy plank at the 1976 convention.

But because Rockefeller was blackballed as a "party-wrecker" after he forced his policy views on Goldwater and Nixon, moderates are still paralyzed by fear of retaliation when they contemplate challenging parts of the conservative dogma.

Whatever the reason, a once-proud tradition is dying, leaving only such sad echoes as that recent unnoticed press conference.