Some of this town's 43,000 HEW and Labor Department employees may be hitting the picket line rather than the lunch line on Friday. The issue is money.

If the demonstrations come off, they also could involve thousands of federal workers in Los Angeles, New York, Philadelphia, Chicago, Dallas, Miami and other big cities. The Social Security center near Baltimore has more than 20,000 workers, and is billed as the largest single white-collar operation in the world.

Congress still hasn't approved the [WORD ILLEGIBLE] needed to fund Labor-HEW operations for the fiscal year that began Oct. 1.Part of funding Labor-HEW operations is paying the several hundred thousand employees of those two agencies.

The Senate and House adopted last week a "continuing resolution," which permitted the last payroll to be met, although some Labor Department workers were short-checked and later issued supplemental paychecks. But that continuing resolution expires next Monday.

All that is blocking approval of the Labor-HEW appropriation bill is touchy language that would set federal policy for paying for abortions. The Senate and House have voted more than a dozen times but have been unable to reach a compromise. Meantime the clock is ticking.

Congressional sources expect that agreement will be reached this week or maybe even today. But if there isn't a settlement, and Congress sticks to its plan to adjourn Nov. 4 there could be trouble here and around the country from employees of the two agencies.

Union leaders from the Office of Education, HEW headquarters office and Labor Department met yesterday afternoon at the national headquarters of the American Federation of Government Employees. AFGE represents most of the two department's workers and has been under heavy pressure from the rank and file to take action.

AFGE president Kenneth T. Blaylock says that if the union doesn't have a solid signal that the money impasse has been cleared up by Friday, action will be taken.

It won't be a strike or slowdown, national union officials say. Rather, they expect employees will engage in informational picketing - telling customers and people walking by government buildings that welfare money is in trouble. Social Security payments could be delayed and the like. Between the two of them, labor and HEW send some kind of check to almost one of every seven Americans.

"This won't be a strike," an AFGE official said. "It will be a demonstration. It isn't the boss who has screwed up. The idea is to let people know that things like black-lung benefits and other payments may be cut off."

If the Senate and House can't reach agreement on the abortion language, it would be possible for them to extend the continuing resolution. That would allow pay checks to be issued and programs to remain funded at their pre-October levels. But Senate and House sources say they don't want to do that, "We want to get this over with," a House aide said. "I would expect things to happen very quickly once the conferees get together on this."