Senate Majority Leader Howard H. Baker Jr. (R-Tenn.) said yesterday he is attempting to clear the way for Senate action this month on a simple 10-year extension of the Voting Rights Act.

But a spokesman for Sen. Edward M. Kennedy (D-Mass.) said Kennedy agrees with major civil rights groups that a simple extension would leave unresolved such key issues as whether an intent to discriminate must be proven and whether bilingual election materials must be provided in some areas of the country.

Baker's plan, which he acknowledged could fall apart if a filibuster develops, would substantially advance Senate consideration of the measure.

Enforcement provisions of the 1965 law expire next summer, and Senate action had not been expected until sometime next year.

The House passed a tougher version of the extension two months ago, including new bailout provisions for states and localities that must now get federal clearance to change their voting laws.

These bailout features would be dropped under Baker's plan for a simple extension of the existing law.

Baker also told reporters he is confident that President Reagan will propose "significant, substantial" cuts in benefit entitlement programs in connection with the 1983 budget next month.

He said every entitlement program "except Social Security" is being examined for cuts.

Baker's comments came as representatives of Senate and House Republican leaders reached agreement with the administration on a common numbers base from which to compute savings from the new catchall government-funding bill that Congress must adopt by Dec. 15.

They also produced a "technical draft" of $4 billion in savings, subject to approval of the leaders themselves later in the week.

This is roughly the same amount of savings that Republican leaders attempted to include in an earlier version of the bill that Reagan vetoed last month on grounds that it fell short of his target.

Disagreement over how to compute the savings had been a major stumbling block, and the agreement yesterday on the numbers base was described by Senate Appropriations Committee Chairman Mark O. Hatfield (R-Ore.) as "the miracle of the day."