The partial federal hiring freeze, originally scheduled for a mid-April thaw, will be around at least until the early part of May.

That means, among other things, till will be harder for outsiders to get jobs with Uncle Sam as agencies get even pickier about the three people they can hire to replace every four workers who quit or retire.

President Carter's three-ouf-of-four hiring freeze is intended to force agencies to slim down so they will be near, at or below new job ceilings that all will get sometime next month. When he imposed the freeze on Feb. 28, the President said he hoped to lift it by early April - but hitches have developed.

For one thing, new cabinet officers and their diputies have balked at even minor job cuts that the new ceilings would mean for them. Office of Management and Budget is directing the operation, and experts from OMB have been huddling with their counterparts in other federal agencies to determine which programs can be cut back. That is easier said than done.

Several agencies - Housing and Urban Development and Labor in particular - have resisted initial proposals from OMB.

Overall, as reported here March 16, there will be two levels of cuts. The first will be a reduction of as many as 30,000 of the 48,000 new government jobs requested by President Ford in his final budget. Those cuts for the most part will be paper reductions since the jobs do not exist. The second tier will involve actual reductions - because of new ceilings for agencies - estimated to run about 2 per cent of the total white collar workforce.

Two agencies that will have substantial job cuts as a result of the new, and lower job ceilings, will be Defense and the National Aeronautics and Space Administration.

Defense is the largest employer in government with about half the civilian work force. It normally loses about 9,000 workers a month through regular atttrition as the three-for-four hiring rule will have its greatest in pact on Defense. It will be at least another month before Army, Navy and air Force have exact figures on the impact of the semi-freeze, and some experts predict that the normal attrition 7,000 a month because people who would ordinarilly, leave/tend to stay in their jobs during times of enforced attrition.

Agencies hope to have their new ceilings at least by mid-May and for most, the partial hiring freeze will end shortly thereafter although the pace of hiring may be sluggish this summer.