'Carter White House' on Reagan White House; Former president inches toward Democratic spokesman role

Conspicuously absent from the political scene in Washington, as President Reagan ends his first six months, is a strong national voice for the Democrats. There some signs that Jimmy Carter of Plains, Ga., may attempt to fill that gap.

President Reagan, at Ottawa, is attending his first major conference on international affairs. It involves three issues on which he differs sharply with his predecessor. Mr. Carter negotiated the Salt II treaty for strategic arms limitation with the Soviet Union, which Mr. Reagan has rejected. Reagan also rejected the strong emphasis on "human rights" that Carter made a conspicuous feature of his approach to other nations.

Finally, the Reagan economic package has continued near-record interest rates at home and abroad -- the source of sharp complaints from many of the nations represented at Ottawa. This grows out of a third major difference with the Carter administration. Carter followed a conventional approach to federal taxes and expenditures; Reagan has introduced one of the boldest packages of budget and tax cuts in history. Demoralized Democrats in Congress charge that the program is weighted against the poor and for the rich, but they seem likely to join with their Republican colleagues in approving most of the program.

At the end of six months, Reagan seems genuinely popular with most of the public, although his performance ratings in the polls have dropped conspicuously. The indication seems to be that the public likes the President but isn't sure of his economic program. Also, the Reagan administration has its first conspicuous staff setback: the resignation of the Central Intelligence Agency's chief of clandestine operations under charges of fraudulent securities transactions back in the 1970s.

That's the story at the end of the first Reagan half year. And the GOP President's predecessor is just beginning to break his silence in what may be his first moves toward filling the Democrats' spokesman vacuum.

In comments in the July 19 "Parade" magazine, former president Carter says that the time hasn't come for him to speak out against his successor -- although he agrees that no other Democratic leader has yet captured the attention of the public on partisan issues. And he specifically "reserved the right" to become his party's spokesman, openly criticizing the Reagan administration, "later on."

Actually, Carter has already taken a clear step in this direction with his widely publicized letter July 3 to officials and aides in his administration. In that letter, carried in many papers last week, he directly took issue with Reagan policies such as cutting back social programs and deemphasizing human rights as a factor in setting foreign policy.

Meanwhile, the former chief executive is writing a book based on comments made daily to a tape recorder during his White House tenure. The recordings amount to 5,000 pages. Looking back at those days, he agrees that "there was never an ease of communication between me and the leaders of the press." All signs indicate, however, that Jimmy Carter, perhaps before long, will be back before the press, making comments on public issues, particularly on the three over which he differs most sharply with President Reagan.

Carter made this clear on two earlier occasions: his farewell address, Jan. 14, and his speech, May 17, before the New York Board of Rabbis in New York. In the little- noticed January farewell address, he solemnly warned that the "risk of a nuclear conflagration has not lessened . . . the danger is becoming greater." He charged that "today we are asking our political system to do things of which the Founding Fathers never dreamed." As people "have become more doubtful of the ability of the government to deal with our problems," he said, "we are in" creasingly drawn to single-issue groups." In two other themes he urged protection of the environment, and the protection of human rights abroad -- "the fight against deprivation, torture, terrorism, and the persecution of people throughout the world."

America has never quite known what to do with ex- presidents, of which it now has three. Richard Nixon is a special case, but Gerald Ford and Jimmy Carter are almost inevitably pushed into the discussion of public affairs. If they lack other platforms, the floor of the US Senate is, by law, open to former presidents under a little-known standing invitation.