The assistant majority leader of the Republican-dominated Senate plans to force the White House to go through Congress to try to change federal guidelines for pay raises, promotions and firings.

The rules have already been published in the Federal Register and could go into effect this fall. But Sen. Ted Stevens (R-Alaska) says he wants Congress to decide whether the changes will go into effect and in what form. The effect of the Stevens action would block changes unless both houses of Congress approve them, and that is unlikely.

The White House is proposing federal job "reforms" that would set up a uniform job performance rating system. The system would be used--rather than seniority--to pick who gets within-grade pay raises, promotions and who keeps a job when agencies are undergoing RIFs.

A pending administrative rules change pushed by the White House would revise the government's "last-hired-first-fired" layoff rules. And it would set up a new government-wide job performance rating system that would overshadow seniority in determing who gets within-grade pay raises and certain kinds of promotions. Those changes will go into effect automatically unless Congress blocks them.

The comment period on the proposed rules is up at the end of this month. And Reagan administration officials hope to have some or all of the pending changes put in place administratively by this fall.

But Stevens (up for reelection next year in a state chock full of civil service families) says he will not allow any changes to be made without congressional approval. He plans to put a rules-change ban in pending government appropriations bills. The House, which is controlled by Democrats, is working on language that would also bar the rules change from being made.

Stevens' stance could block, or drastically alter, the administration's plans for changing the rules if he can persuade enough of his GOP colleagues to go along with him.

Many federal employes, and all government unions, oppose the rules change, which would base employes' eligibility for promotion, in-grade raises or RIFs on their last performance ratings, regardless of seniority.

Many members of Congress and federal employes favor a revised system that counts both seniority and performance. One suggested compromise would be legislation that would take into account employes' last three performance ratings--rather than just their most recent one--when raises, promotions or RIFs are being considered.

The battle of the rules change isn't over yet. But the mood in Congress appears to be against any kind of rules change unless the Senate and House have the final say-so on what those rules will be.