Republican House members took a calculated risk yesterday in blocking what could have been half a win on aid to the rebels in Nicaragua, hoping that the delay will build public and congressional support for the whole program.

GOP leaders opted to scuttle a limiting amendment offered by Rep. Dave McCurdy (D-Okla.) that would have allowed $30 million in nonmilitary aid to go to the rebels immediately, assuming the underlying bill passed. A second vote in 90 days might have unlocked $70 million in military aid to the counterrevolutionaries, or contras.

But the Republicans were not sure they had the votes for that underlying measure. They also were angry about the procedural box the Democrats had put them into by tying contra aid to a complex package of supplemental appropriations.

The desire to wiggle out of a trap and thumb one's nose at the trapper was a factor yesterday, and accounted for the roars of glee over the vote from the Republican side of the aisle.

"We'll win notwithstanding your two efforts to beat us down," Minority Leader Robert H. Michel (R-Ill.) shouted at the Democrats, pounding the podium after the vote as his Republican colleagues cheered. "The president deserves better treatment than what you tried to give us here today."

And the Democratic leadership promised soothingly to provide it: House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) sent word he would not oppose any GOP effort to attach contra aid to any appropriate measure that comes along.

Republican strategists said their reasoning was that if delay was inevitable for the military part of the package -- the important part -- then they might as well avoid almost certain defeat on McCurdy, get out of the procedural vise, avoid the supplemental package and befuddle everybody all in one move.

The petition under which Republicans hope to structure the next vote their way would give them a better chance to kill the McCurdy approach and would eliminate an amendment by Rep. Robert J. Mrazek (D-N.Y.) that would keep U.S. military and American employes of the government out of combat zones.

They plan a renewed campaign to build support for the contras and hope that this week's U.S. raid on Libya will help in that effort. Republican pollster Richard Wirthlin spoke to reporters yesterday before the vote of a "halo effect" that the attack on Libya is likely to produce for President Reagan. Later, in the floor debate, Republicans tried hard to tie Libyan leader Muammar Qaddafi to Nicaraguan President Daniel Ortega, and there is no sign that effort will diminish in the coming weeks.

It is also an article of Republicans' faith that if they can just get the word out to the American public about the dangerous nature of the leftist Sandinista government of Nicaragua, support for an unmodified aid package for the contras will force Democrats to get on board.

The Democrats' early morning head count yesterday found 68 of their number undecided on how to vote on McCurdy's proposal, reflecting the continuing division in the country on the contra aid issue.

Wirthlin said public ignorance about the question is "discouraging. When we ask people to tell us where Nicaragua is located, only a third can tell us it's in Central America." However, he said that awareness is rising and that Republicans are convinced that increased awareness will help their cause.

On the other hand, Democratic leaders seemed sincere when they expressed amazement at the GOP move, calling it suicidal. They noted that the polls show not only public ignorance but also strong sentiment against renewed U.S. backing for the rebels, and they take heart at the steadily declining margin of Senate votes approving aid.

In fact, one key Republican strategist noted yesterday that the question of providing aid to the contras brings together three strong negatives in the public mind: Vietnam, in which the vision of American boys dying in a jungle is "engraved on American 'brain-pans' "; foreign aid, which always ranks last on any list of priorities; and the notion of interfering in another nation's affairs, a taboo that the United States usually honors in the breach.

Delay, said one Senate Democrat, "only means more and more people raising more and more questions."