The glow that brightened House Republican faces after they scored a tactical victory over the Democrats began to fade yesterday as the congressional battle over aid to the Nicaraguan rebels moved into a new phase.

The Republicans on Wednesday won the week's battle over parliamentary procedure, but, when it was over, the Democrats' long-term strategic position against President Reagan's proposed $100 million aid package did not appear to be seriously weakened.

With its action, the GOP started down a long, difficult and unorthodox road toward what their leader, Rep. Robert H. Michel (R-Ill.), called "a clean shot" on the aid issue.

The Republicans' tactical victory came when they short-circuited the debate on aid to the counterrevolutionaries, known as contras, preventing a vote on a compromise that appeared to have a good chance of succeeding. The compromise, sponsored by Rep. Dave McCurdy (D-Okla.), was unacceptable to the White House and the House Republican leadership, so they blocked its consideration in the hope of later forcing a vote on the Reagan aid package.

To do that, the Republicans next week will begin circulating a "discharge petition" that, if successful, would bring to the House floor another legislative vehicle dealing with policy in Central America. They have structured this latest maneuver so that the final item the House would vote on, next month at the earliest, would be an exact duplicate of the Senate-passed contra aid plan that the administration supports.

If adopted by the House, this measure would go directly to the president for his signature, bypassing a return to the Senate, where it faces a possible filibuster and other hurdles.

"It's a tough task," House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) said yesterday of the discharge petition method.

That may be the only observation about the entire dispute on which O'Neill and his Republican counterparts agree. "It can be done and will be done in time," said House Minority Whip Trent Lott (R-Miss.).

But time is moving on in this Congress and in Central America, where the administration says the rebels face annihilation by Nicaragua's Sandinistas if they do not soon receive U.S. military assistance.

Lott acknowledged yesterday that the GOP's first target date for a resumption of the floor debate on contra aid -- May 12 -- is probably not realistic given all the political and procedural land mines along the discharge petition route.

He also said the Republicans are already eyeing alternative methods to get their way, which he would not discuss. "They [the Democratic leaders] have to realize that there are other ways to get this to the floor and that we're smart enough to use them," Lott said. "We're open and willing to talk to the Democrats about another vehicle."

Behind all this tactical and parliamentary maneuvering is a cold political calculation by the Republicans concerning a key group of moderate to conservative Democrats who supported the McCurdy proposal. When the House initially rejected the Reagan aid package on March 20, O'Neill held the Democratic majority together by promising this group they would get a second chance to vote for some form of contra aid this month, in connection with consideration of the fiscal 1986 supplemental appropriations bill.

The Republicans saw this move as a way for O'Neill to protect Democrats from conservative districts without really aiding the contras. McCurdy and the others would have their "political cover" -- a vote for contra aid with limits on its use to point to during the fall election campaigns -- but the funds, because they were attached to a spending bill that could take months to enact and may be vetoed, would never reach Central America.

So, in the words of Rep. Dick Cheney (R-Wyo.), the Republicans kept the moderate Democrats "on the hook" by denying them the chance to vote for the McCurdy proposal.

That worked, but the discharge petition faces several more obstacles. Even if all Republicans, including the handful who oppose contra aid, sign it in a show of party solidarity, GOP leaders will still need the cooperation of 36 Democrats to reach the required 218 signers, a majority of the House.

A discharge petition is a form of legislative guerrilla warfare, an unorthodox maneuver around the normal rules and procedures of the House. As the majority that controls the legislative machinery, the Democrats have a vested interest in preserving the established rules. This is true even for those who support aid for the contras, particularly a number of conservative committee chairmen who rose to power by playing by the rules.

The Democratic leadership has not made the discharge petition a party loyalty issue, but it will work vigorously against it. O'Neill said yesterday he no longer was "under any obligation" to provide another vote on contra aid, but in his own tactical countermove he had already promised the moderate Democrats a chance to attach the McCurdy proposal to Defense Department legislation due to be considered in June.

Sometimes a discharge petition succeeds. The most recent example involved the legislation to weaken the Gun Control Act of 1968, which was forced onto the House floor by this procedure last week. In this case, it not only took time but all the political muscle of the National Rifle Association to round up the necessary signatures.

What has been missing in the contra aid debate from the administration side is that kind of public pressure on Congress to back administration policy. Michel seemed to acknowledge this Wednesday. Citing a recent poll, he said, "This is an astounding fact. After six years of debate and discussion and evening television news, only 38 percent of the American people know which side [in Nicaragua] the administration is supporting."

In this context, the best the Republicans could do in the House this week was to buy themselves some time and hope to use it to change public perception of the debate.