The Senate is supposed to take up Tuesday, and pass, legislation by Sen. Ted Stevens (R-Alaska) that would continue the government's AWS (alternate work schedule) program.

The AWS program makes it possible for federal employees to work 10-hour, four-day weeks (by voluntarily waiving overtime), and it encourages agencies to let employes stagger or "flex" their hours.

Authority for the current AWS program runs out in mid-July. Unless the program is extended, everybody now working four-day weeks will have to return to the five-day week.

Ending the AWS program would not automatically abolish flexitime, since it requires no overtime payment. While many agency heads don't like the flexible hours program and could be expected to drop it if AWS ends in July, some find it useful.

The FBI, for example, has many employes working the four-day week and flexitime shifts. If Congress fails to extend the AWS program, the FBI will have to terminate 10-hour-day (without overtime) schedules. But the FBI intends to keep the flexitime program going.

The Senate is expected to approve Stevens' bill. The House is prepared to act on the Stevens bill or, if it falters, to approve a similar measure by Rep. Geraldine Ferraro (D-N.Y.).

In any case, the AWS program must be approved by President Reagan before the third week in July, or the four-day week -- and many flexitime programs -- will go down the tubes.