Dallas — As the small group headed for a reception for Republican moderates and liberals, one GOP convention delegate quipped that at least they had enough people to fill an elevator. And they did, just barely.
So total has been the dominance of the right wing here that voices of moderate or liberal dissent are an oddity that calls for several television cameras and news-starved reporters on the convention floor. Most of the party's stalwart moderates are holding their fire, despite passage of a platform that goes farther rightward than President Reagan.
''This platform is going to be little-read and less remembered,'' says Sen. John H. Chafee, a moderate from Rhode Island, who declares that he doesn't take the development too seriously.
But while few words of despair are heard at this upbeat and pro-Reagan celebration, some of the party's moderates are conceding they had been sitting idle, while the conservatives worked in the grass roots. And some are vowing that they have been shocked into action after the November election.
''The moderate wing of the Republican Party has been an 'elitist' group that failed to believe that they had to get down and grub'' at the precinct level, Sen. Nancy Landon Kassebaum of Kansas said Wednesday at a breakfast with reporters.
As for the platform, she said she had disagreements, particularly on social issues, such as its strong anti-abortion stand and lack of support for the proposed Equal Rights Amendment. But the Kansan saw the platform as a catalyst for debating the future of her party.
''This political platform doesn't try to compromise or hedge,'' she said.
Already the strong offensive from the New Right has triggered a reaction among a tiny group of moderate-to-liberal Republicans, led by Rep. Jim Leach of Iowa.
Taking pages out of the book of a group of firebrand conservatives in the House, Representative Leach is launching the Republican Mainstream Committee, which he says will strengthen the sagging middle in the party.
''The moderate Republican philosophical house has been out of order,'' says Leach. ''Moderates came to stand for in-betweenism. That ain't good enough.''
He credits the right wing of his party with ''putting forth national ideas,'' while the moderates focused on the skills and techniques of legislating.
''The question is whether the moderates can come back and declare that they have a national vision,'' says Leach. As a starting point, the mainstream group has produced a ''manifesto'' in which Leach harks back to his party's commitment to ''individual rights,'' civil rights, and environmentalism, all of which he says have roots in the GOP's past.
Although the New Right won on most of the platform planks, Leach concludes the next question is whether ''this is the death knell of the moderate wing or the beginning of a swing back.''
The fourth-term congressman began in earnest at the convention to begin shoving the pendulum back. He took his crusade to the platform hearings and to the new media. But he has had few vocal supporters among GOP officeholders. ''Reagan is so personally popular that it's hard'' to speak out at the convention, he explains.
Rep. Marge Roukema of New Jersey, for example, concedes some misgivings about the platform, but she says now is not the time for protest. The moderates should begin their move ''the day after Ronald Reagan is reelected,'' she says.
''Although one doesn't like it, it has to be expected,'' she says of the right-wing dominance of the platform. ''What it says for me is we have to work very hard ... to forge a broader consensus of public opinion in the next four years.''
Meanwhile, moderate GOP officeholders and candidates are arguing that the conservative platform will not hurt their campaigns. The central issue in 1984 is not ideology but President Reagan's popularity, says Senator Kassebaum. ''I think that there are many people ... who even may not agree with the President on a great deal'' but who will vote for him anyway, she says.
Leach takes encouragement from what he sees as an underlying ''tension that's going to be very helpful for moderates in the next few years.''
He and other moderates warn that unless the party heeds them and broadens its tent, the GOP will lose voters.
But that issue will have to be fought out at another location, since here in Dallas nearly all disagreements are hidden in the shadow of a President who, participants say, will win by a landslide.