ORLANDO, FLA., SEPT. 20 -- Three Republican presidential candidates appealed for the support of some of the nation's most effective political activists today, the 2,500 women attending the convention of the National Federation of Republican Women.

Sen. Robert J. Dole of Kansas contended that he is the most electable for 1988. Television evangelist Marion G. (Pat) Robertson claimed that he embodies the issues that could make the GOP the majority party for the rest of the century. And former secretary of state Alexander M. Haig Jr. cited his experience in the executive branch.

Dole told the women that they are "the type who work and work and work to get us candidates where we want to go." Haig praised them as being "the bone and the marrow of the Republican Party."

Appearing at the windup of the three-day convention, Dole, Robertson and Haig followed the Saturday appearance of Vice President Bush, Rep. Jack Kemp and former Delaware governor Pierre S. (Pete) du Pont IV.

Like Kemp and du Pont before them, Dole, Robertson and Haig voiced varying degrees of reservation about President Reagan's proposed agreement with the Soviet Union to eliminate medium- and shorter-range nuclear missiles. But they concentrated on trying to sell the attentive but undemonstrative audience on their candidacies.

Interviews with some of the delegates after the candidates had spoken indicated that most still have not settled on a choice.

Dole told the women the issue is "which of us can be elected. The bottom line in 1988 is to keep the White House Republican."

He said he could "attract more independent and Democratic voters, which we need to, because you can't be elected just with Republicans." He told reporters afterward that Bush "doesn't do as well with independents and Democrats as I do."

He said that in 1976 and 1980 the voters elected presidents who "had no Washington experience, but now the pendulum has swung back. The American people want someone with experience, someone who can work with the Congress, someone who is sensitive to the needs of a wide range of people, someone who can make the hard decisions and get the job done."

Dole predicted that the Senate will confirm Judge Robert H. Bork for the Supreme Court and said that the proposed arms control agreement "is a step in the right direction . . . . But the bottom line of any ratification is that we can verify it, that the verification procedure is airtight and we'll make sure it's airtight."

He said he was confident Reagan would not negotiate a treaty that "somehow is flawed. It just is not going to happen."

Robertson called for a "spiritual and moral revival." He said that 6,000,000 former Democrats, mostly evangelical Christians, have switched parties because the GOP represents a "philosophy of life and government that mirrors the hopes and dreams and aspirations of a majority of the American people."

"If we are bold enough to speak out against communist tyranny, bold enough to speak out for free enterprise and against the encroachment of big government, bold enough to speak out for the family and social values that are tugging at the heartstrings of the American people, then the Republican Party will not be the minority party but the one that is destined to govern the United States for the rest of the 20th century."

Haig said that in the Reagan years "the American people have experienced a renewal of spirit and respect for traditional American values." He criticized the Democratic presidential candidates, whom he described as "the so-called seven dwarfs about to be joined by Snow White," for holding "a grim Malthusian attitude" of malaise that is a "throwback to the sophistries of the past."

He was especially scornful of Sen. Paul Simon of Illinois, who he said "wants to go back to the New Deal."

Haig told the women that they should back a candidate who, like him, has had executive branch experience, success in the private sector and experience in foreign affairs.

"If he cannot meet these criteria, this is no man to lead America into the turn of the century," Haig said.