The House Post Office-Civil Service Committee, over the objection of most of its Republican members, will approve a 4 percent October pay raise next week for 1.4 million white collar federal workers whose job titles range from stenographer to astronaut.

Democrats who control the committee agreed last week to go with the October pay date, despite a tentative budget worked out by Senate-House budget conferees that would delay the raise until January. Neither proposal is satisfactory to President Reagan, who wants to delay the raise until the fall of 1984.

By law, white collar federal workers are supposed to be paid salaries equal to those for similar jobs in the private sector. The Bureau of Labor Statistics makes a private industry pay survey each March and its data forms the basis for the so-called comparability raise.

But Presidents Nixon, Carter and Ford all rejected the "comparability raise" recommendation as being too high. Each submitted alternative (lower) raises without congressional objection.

According to BLS data, federal workers last year were due an 18 1/2 percent catch-up-with-industry raise. But they got only 4 percent.

If the Budget Committee and the full House go along with an October pay-raise date it -- other differences in the Senate and House versions -- again will go to a joint conference committee. The first Senate budget recommended the federal pay raise be held off until April 1984. But in conference it agreed to the January 1984 date.

The bad news is that, because of the budget process and the strong presidential authority under the federal pay law, it could be early September before the white collar workers -- there are 360,000 of them in the Washington/Baltimore area -- know when they will get their next raise.

The good news is that the pay-raise issue is far from dead, despite the president's opposition.

Both the House and Senate have rejected the no-raise idea. That is good news for feds and for the Washington metro area, which enjoys the federal payroll that is now running about $1 billion a month.