President Carter's call for resumption of registration for the draft introduces a dramatic new factor into the lives of about 16 million young men ages 18 to 26, and could well become an issue in the presidential election campaign.

In terms of U.S. foreign and defense policy, it is partly a gesture, a signal to Moscow of America's determination to protect its interests.

It also may represent a first step in grappling with the problems of the all-volunteer Army. The familiar statistics of that endeavor suggest that this six-year-old experiment is not producing as large an army as the nation might need in a crisis.

Today's U.S. Army, with 765,600 people -- eight percent of them women -- is the smallest in 30 years. The absence of the draft, or even the threat of one, has also left Army Reserve and National Guard forces about 134,000 short of peacetime objectives. The Soviet Army, with about 1.8 million soldiers, is more than double the size of its U.S. counterpart.

Administration officials said last night it would be several months before the necessary rules could be worked out and registration would take effect.

It was not clear last night how registration forms might be distributed. Officials said the government might have registrants pick them up at local post offices.

Carter said he hoped it would not be necessary to reinstitute the draft itself, as opposed to registration, which he described as a precautionary device.

Even so, initial reaction was mixed.

Congress must take a stand on the issue, and Carter said he is requesting an appropriation to set up a registration system. House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) indicated he would support the president, and Senate Majority Whip Alan Cranston (D-Calif.) said he thought the forthcoming legislation would "probably" be approved.

House Minority Leader John Rhodes (R-Ariz.) also predicted Congress will go along with registration.

Republican presidential candidate George Bush, the GOP winner in the Iowa caucuses earlier this week, long has favored renewal of registration. Carter's Democratic rival Sen. Edward M. Kennedy (D-Mass.), had no comment on the president's message last night.

Such longtime proponents of a return to the draft as Rep. Paul N. (Pete) McCloskey Jr., a liberal California Republican, also expressed predictable support.

Another liberal Republican, however, sharply criticized the decision. Sen. Mark Hatfield (R-Ore.) said "hysterical voices" calling for a return of registration and the draft are further evidence of the administration's "bankrupt foreign policy."

And Sen. George McGovern (D-S.D.) had warned in an interview last week that the country would pay a heavy price in domestic divisions and strong reactions on campus, recalling Vietnam protests, if it moved back toward the draft.

David Landau, a leader of the American Civil Liberties Union which opposes the draft move, said groups of organizations were prepared to mount a national campaign to stop it.

Carter's call for revival of registration was opposed by several congressional conservatives -- for example, Sen. William Armstrong (R-Colo.) and Rep. Philip Crane (R-Ill.). Both said they favored a volunteer army thought it would still work.

Public opinion polls in the past year, however, have shown growning public suport for at leaast renewed registration.

In March of last year, a Gallup poll showed the public evenly divided on resuming the draft but strongly in favor -- by 76 percent to 17 percent -- of registration.

A Washington Post poll of some 2,500 persons nationwide in November showed 55 percent agreeing that all physically fit young men should serve in the armed forces with 38 percent opposed.

Although the draft was only a wartime measure for much of early American history, it became a steady fact of life, beginning in 1970, for millions of young men.

With the exceptions of 1947 and 1948 some 15 million youths were drafted between 1940 and December 1972, when the last draft calls went out. Millions more volunteered under the pressure of being drafted.

In July 1973, the president's induction authority was allowed to expire and the country moved toward an all-volunteer force faced with the formidable task of trying to persuade, and lure with higher pay, some 500,000 young men and women a year to volunteer.

The Nixon administration's effort to end the draft was politically popular at the time and also helped take some of the heat off the administration as it grappled with Vietnam.

By last year, however, it had become clear that the military was falling short of its recruitment goals. To make matters worse, population figures show that the pool of qualified 18-year-old men able to serve, now about 1.78 million a year, will drop to 1.5 million in the mid-1980s and 1.3 million in the 1990s.

Some believe that higher military pay, or higher civilian unemployment, could boost the Army's appeal and reverse the recruitment trend.

While the Pentagon insists it has enough troops now to carry out the official policy of being able to fight one big war and one small war simultaneously, many top military and civilian specialists say the United States would quickly run out of troops in any sustained war. Army generals say the United States would be 100,000 men short within 30 days of the outbreak of a war in Europe.

The Selective Service System is supposed to be able, according to Defense Department requirements, to supply the first soldier to the Army within thirty days, 100,000 men within 60 days and 650,000 men in 18 days.

The 1,800 old neighborhood draft boards, however, are gone. What is left of the Selective Service System as of today is the heaadquaraters staff in Washington and six regional centers around the country.

Though it takes action by Congress to actually reinstitute the draft, the president has executive authority to order registration.

The president would need new legislation if the registration eventually is designed to cover women as well as men, a move that would then affect another 16 million or so young Americans.