House leaders worked yesterday to protect a bipartisan agreement that would limit House members' spending on "franked" mail and to head off deep cuts in Congress's own budget when it reaches the floor this afternoon.

With lawmakers fearful of an anti-incumbent revolt among voters, the $1.7 billion appropriations bill for the legislative branch for fiscal 1991 is viewed as a tempting target just before congressional elections.

Proposed changes in the way members are allowed to send mass mailings to constituents at taxpayers' expense are expected to be a major point of contention. Another issue expected to spark debate is a plan to increase salaries for House members, top House officers, and committee and personal office staff.

After two years of internal fighting, the House for the first time is expected today to vote for a yearly limit, averaging $178,000 for each member, on how much lawmakers may spend to mail material back home. The proposal, put together by Rep. Vic Fazio (D-Calif.), chairman of the House Appropriations subcommittee on the legislative branch, and Rep. Bill Frenzel (R-Minn.), also would require quarterly public disclosures by each member of mailing costs. These would allow monitoring by the postmaster general.

If a legislator is found to have exceeded a spending allocation, the U.S. Postal Service "may not carry or deliver official mail" from that member, according to the Fazio-Frenzel proposal.

As a result of the changes, costs of House mailings would drop to $59 million for fiscal 1991, down almost $20 million from spending during this election year.

A House source familiar with mailing practices said "a member backlash" is brewing as some lawmakers read the Fazio-Frenzel proposal and realize it would reduce their current use of the frank.

Traditionally, opposition to any change in the unlimited right to send franked mail without public reporting has been led by Rep. William D. Ford (D-Mich.), chairman of the Post Office and Civil Service Committee. Ford remains opposed, an aide said, because he considers the proposed overhaul "unworkable" and "too costly to maintain."

Since House rules will prevent any amendment to the Fazio-Frenzel plan, some members fear that if it is defeated, an even sharper cut will be voted in funds available for official mail, as members try to show they are not seeking to exempt themselves from budget cuts.

To meet the new budget resolution goal adopted last week by the House and to ease pressure for more reductions, Fazio today is expected to propose trimming $26 million from the bill approved by the House Appropriations Committee in July. About one-third of those cuts would come from House operating funds and the rest from other agencies covered by the bill, such as the Architect of the Capitol, General Accounting Office, Library of Congress and Government Printing Office.

The legislative branch bill also contains funds for pay raises voted earlier this year for House members -- whose salaries are set to increase Jan. 1 from $96,600 to $125,100 -- and for salary increases for House officers, such as the sergeant at arms, and top committee staff members. Fazio said attempts to cut these funds are expected to be ruled out of order.

To allow lawmakers' personal staff aides also to get raises, Fazio added $16 million in the bill's overall "clerk hire" account. However, an amendment expected to be offered today would cut this allotment. According to House sources, the amendment would leave untouched pay increases for House members, officers and top committee staff.

Wide disparity exists in House pay and, according to House sources, this proposal would worsen it. Last year, for example, only one House Appropriations Committee staff member, the staff director, was paid more than $80,000 a year. But seven House District Committee staff members received higher salaries, including $88,000 paid to the staff director.

"There are a lot of hard feelings about the salary increase," Fazio said yesterday, "and I don't have the votes to sustain an increase for personal staffs."