On Capitol Hill they are called the ''reasonable ones'' - the Republican senators who didn't always like the turn of events, but who usually went along without much fuss. These moderate-to-liberal GOP lawmakers watched from the outskirts for two years while others made decisions.
Now they are no longer content to watch. A band of five GOP senators is rejecting the 1984 budget proposal worked out by the Republican leadership. And since their party holds only a four-seat majority in the upper chamber, suddenly the docile moderates begin to look like power brokers.
On the surface, they are decrying the gigantic federal deficit, which they say endangers the economic recovery. But in interviews, senators and staffers indicate that the moderates are aiming higher. They want to change the drift of the Republican Party toward the right.
''We feel more moderate voices of the Republican party ought to be listened to,'' says Sen. Robert T. Stafford of Vermont, a member of the so-called ''gang of five'' Republican dissenters. The group has been meeting for at least two months, and they made their first public move by proposing a federal budget that would cancel the 10 percent Reagan income tax cuts due to begin in July.
The GOP moderates will not stop with the budget, says Sen. Mark O. Hatfield of Oregon, another of the gang of five, whose members also include Senators Lowell P. Weicker Jr. of Connecticut, Charles McC. Mathias Jr. of Maryland, and John H. Chafee of Rhode Island.
''We're going to associate ourselves to look at every issue that confronts the Congress,'' says Mr. Hatfield, citing the debt-ceiling limitation, the MX missile, and immigration reform as the next issues on which the group will attempt to flex its muscles.
The Oregon senator, one of the few GOP lawmakers who accepts the label of ''liberal,'' maintains the moderates are ''not power brokers for the sake of power,'' that they have ''no personal objectives'' and are ''not trying to set (themselves) up as burs under the saddle'' of the Senate GOP leaders.
Behind much of the uneasiness is concern over the 1984 elections. Most of the moderates are from the Northeast and Midwest, areas hard hit by joblessness. Republicans already suffered setbacks and near-losses during the 1982 elections, and next year 19 Senate Republican seats will be up for reelection.
''We feel we can strengthen the Republican party policy in '84 by broadening the base,'' says Hatfield, whose term will be up. He says he has not decided whether to run.
If the gang of five is small, they have kindred spirits among their GOP colleagues. Sen. Arlen Specter of Pennsylvania, for instance, objects to ''strident positions'' taken publicly by the five, but he shares many of their views. He wants to reduce deficits by delaying the July income tax cut, and, as of a May 6 interview, had still not signed on with the Republican leadership budget plan. He also wants the Republican party to stretch its tent to accommodate more ''diversity.''
''There're lots of different points of view in the country,'' says Mr. Specter. ''And if the party is going to be in a leadership position, then within our party we have to have lots of points of view.''
Behind the moderate revolt, there also lurks a memory that some right-wing GOP senators, notably Jesse Helms of North Carolina, have openly defied the White House, while the moderates made little trouble, even as the party tilted right. Now some want to stop ''burning incense at the shrine of the right wing, '' as one Republican put it.
Meanwhile, Senate Majority Leader Howard H. Baker Jr. (R) of Tennessee and Senate Budget Committee chairman Pete V. Domenici (R) of New Mexico must work out a budget agreement this week.
Mr. Domenici argues that the Republicans should back his proposal, since there is little argument over defense and domestic spending figures. He holds that even the deficit would be about the same (about $192 billion in fiscal year 1984 according to the Domenici budget), because Congress would not vote to raise
''I'm the first to admit that these are very risky economic times,'' Domenici told reporters last week. But he added that there is ''less risk if you just don't rock the boat dramatically'' by repealing the '84 tax breaks.
So far his logic has failed to convince the required 51 members of his party to put through a budget resolution. The moderates complain that neither the Senate leadership nor the White House has shown any flexibility about tax figures, and so the budget appears to be deadlocked.
Some of the holdouts are in the Senate leadership, and are expected to revert to their former ''reasonableness'' in the end. But not before they have made the point that they want to be heard among decisionmakers.