The Senate Rules Committee is scheduled to consider a resolution today that could result in an increase of nearly 50 percent next year in taxpayer-financed franked mailings by senators.

The new proposal, backed by Committee Chairman Wendell H. Ford (D-Ky.) and the ranking minority member, Sen. Ted Stevens (R-Alaska), could lead to cancellation of cuts in Senate mailing privileges made last year. The Senate has been torn between the desire to continue making mass-mailings to constituents at taxpayer expense, and concern that the growing cost of such mailings is politically embarrassing.

Although the resolution contains no figures, the plan has been drafted with the expectation that the Senate would vote to spend $35.5 million in the fiscal year

beginning Oct. 1, 1990 for mail,

according to staff aides. That fig- ure would cover the equivalent of two mailings to each address in

the nation plus an additional amount for Senate committee mailings and a small contingency fund, aides said.

The new legislation being considered today would also allow senators to save up their mailing allocation, in effect, for use in the year before they next stand for election. The result could be heavy mass mailings in the election year, but few if any until then.

The $35.5 million, which is a marked increase over the $24 million voted for this election year, would have to be approved by the Senate Appropriations Committee and by the full Senate and House before it became effective. The Senate's legislative appropriations subcommittee has led the fight in Congress during the past two years to cut the costs of official mail.

The proposed increase comes at a time when senators are not using up the amounts allocated to them from this year's $24 million appropriation, according to the U.S. Postal Service's analysis of Senate mailings over the first six months of the fiscal year.

Ford said yesterday that his proposed new plan was the "fairest" that could be put together. He added that members needed the extra money above this year's figure to cover increases "in population and costs of mailings" and that if "there is money left and we don't spend it . . . we can reduce the amount next year."

In fact, Congressional Research Service figures show that only a tiny fraction of senators' mailing costs goes to individual letters -- business mail or responses to constituents' queries or requests. The overwhelming amount is spent on mass mailings that blanket a senator's state, or go to members of selected sub-groups of the state's population.

Although the Senate has led the way in limiting the increasingly costly use of official mail, Ford decided late last year that the amount voted for the current year was too low. Ford is running for the post of majority whip in the Senate next year, a post now held by Sen. Alan Cranston (D-Calif.).