Top AFL-CIO postal and federal union leaders will spend part of this morning at the White House hearing about labor law reform. Wednesday they will return for some "jawboning" about the 1978 federal pay picture.

President Carter already has clamped a 5.5 percent lid on this year's white collar federal and military pay raise. The increase normally a catch-up with industry, is being kept down in an effort to persuade the private sector to restrain wages and prices voluntarily.

The main target of the Wednesday talks will be the U.S. postal Service contract, the biggest (600,000 employes) single wage package of 1978. The president will call in the first team, including the secretary of labor and anti-inflation czar Robert Strauss, to try to persuade postal union leaders to join in the mandatory sacrifices that their white collar colleagues must make. It will not be an easy chore.

White collar federal salaries represent the only segment of the giant $69 billion government payroll that the president can control directly (with the consent of Congress). Postal workers bargain with the U.S. Postal Service for wages. Blue collar (wage board) government workers get automatic raises that are linked to the going rate in hometown private industry.

So far this year the blue collar government pay increases that have been approved have averaged better than 8 percent.

The real target of the Federal anti-inflation drive, however, is the nation's rank-and-file postal workers. Their contract is up in July. More than 85 percent of the work force is union, and members are demanding substantial pay increases, cost-of-living guarantees and improved fringe benefits as the price of staying on the job.

White House officials are worried that a "generous" postal contract could set the stage for higher demands from private industry. Postal union leaders believe that there already have been enough "generous" industry wage increses to justify their trying to match or exceed their current contract. In this agreement, the unions got members three pay raises, six cost of living increases and the promise of the U.S. Postal Service not to lay off workers because of automation.

USPS leaders - who say they can't afford to be as generous this year and postal officials have made it clear that they want the White House to keep hands off their negotiations. But the Postal Service probably would not object if Carter could persuade unions to lower their sights a little.

Union chiefs say they will be especially careful at the Wednesday meeting. It will be the one about money, and will be held in the Indian Treaty Room. "A lot of people got the shaft making agreements in that room," said one union leader from the far west. "But it won't happen to us."

Rank Discrimination? Many HEW employes are bitter because the new early-out retirments option for their big department applies only to people in Grade 12 and above. More than 70 percent of HEW's work force is below that grade level, meaning they cannot take advantage of the early retirement bonus.

HEW originally asked the Civil Service Commission for permission to let anybody, at any grade, retire early if they met the minimun age and service requirements for the early-out option.

Under the law, federal agencies can let senior workers retire early if the Civil Service Commission determines that agency, or portions of it, is facing a major reduction in force, CSC can give the early-out to an entire agency, limit it to specific geographic areas, or to certain grades. That is what it did in the case of HEW.

The Commission, now HEW, determined that the impact of reductions in force would not be severe enough below Grade 12 to warrant the special early-out authority. So, CSC gave the optional retirment benefit to HEW but with the understanding that nobody below GS 12 could exercise it.

HEW management is getting a black eye from workers who think the department sold short the lower-grade workers. But CSC officials confirm that HEW did try to get the early-retirement option for all grades, but was turned down.

The latest figures indicate that approximately 3,600 Grade 12 and above jobs in HEW are targets for some sort or "adverse atcion." Below Grade 12, which is where most HEW workers are, less than 2 percent of the jobs now are slated for adverse action.