Optimists in government and Congress believe (hope) the Reagan administration will give very quiet support to $8,000 October catch-ups for some U.S. executives in addition to providing them with the same 4.8 percent raise due more than a million nonexecutive white-collar federal workers in a couple of weeks.

Administration officials told Congress yesterday that the president wants government supergraders and members of the Senior Executive Service to get the same scaled-down raises he has proposed for civil servants in Grades 1 through 15. That is less than one-third the amount the government says it would take to equalize mid-level U.S. pay rates with the private sector.

Insiders say the White House endorsement of a 4.8 percent raise for government executives -- made by Office of Personnel Management chief Don Devine -- is as far as Reagan will/can go publicly on the always dynamite issue of raises for the predominantly Washington-based bureaucratic elite.

Congress has kept top federal pay frozen at $50,112.50 for the last two years. During that time, salaries of rank-and-file feds went up more than 16 percent. Pending legislation in Congress would maintain that $50,112.50 cap. Reagan wants it raised by 4.8 percent. That will be considered too little inside the beltway, and too much by taxpayers outside of Washington.

The administration's official position is that executives should get what subordinates do this year. It does not touch, even with a 10-foot pole, the question of catch-ups.

Reagan is over a self-designed political barrel. He has denounced federal spending, made a production with his federal hiring freeze, brought layoffs to government and cut politically sacred cows all over the place. He will ask even bigger cuts, including chops in the once-untouchable Pentagon.

On the other hand, he has heard from high-priced Cabinet aides that they can't get, or keep, the kind of people they want on what Uncle Sam pays his top people. Besides heavy relocation costs, some top officials who came to high-cost Washington (taking pay cuts in the process) are now saddled with two mortages -- their new homes here plus the ones the cannot sell back home.

One senior official said it "took a lot of guts and soul-searching" for Reagan to come out with the modest 4.8 percent raise proposal for executives. He said that optimists -- i.e. the Senior Executive Association and some sympathetic members of Congress who want a "full fix" (that is the 1981 raise of 4.8 percent plus catch-up adjustments of more than 16 percent for 1979 and 1980) are "less than realistic" if they expect anybody on the Reagan team to go all out for bigger executive raises, which play well in Washington but draw boos in Peoria.

It boils down to this: Reagan would be delighted if Congress forces the issue of 21-percent-plus catch-ups for executives. But he won't go out on the limb if he spots any member of Congress with a political ax.

Reagan's troops will not rush Capitol Hill if Congress removes the executive pay cap completely, allowing executive salaries to go to a maximum of around $61,300. But if conservative Republicans or spoilsport Democrats (who would question cuts in school lunch programs while executive pay is going up) make an issue of executive catch-ups, the White House will drop the idea like a bad habit.

What to Watch For: The House will probably approve its version of the legislative branch appropriation bill next week (the new fiscal spending year starts Oct. 1). It will probably retain language keeping the executive "cap" on for another year. Meantime the Senate is expected to come up with a "continuing resolution", minus the executive pay cap, to allow Congress to keep running pending a formal appropriation agreement.

Then Senate-House conferees will decide what sort of executive raise, if any, to allow. Insiders say the president will go along with whatever Congress decides but not propose anything beyond 4.8 percent. That is what is known in Washington as a very positive, negative approach.