The Senate continued to wrestle yesterday over extending the Voting Rights Act, postponing until at least Tuesday a vote on a routine procedural motion to begin consideration of extension legislation.

More than 80 senators--along with the Reagan administration--have expressed support for a compromise bill that would substantially strengthen current law. But Senate conservatives, led by Jesse Helms (R-N.C.), have threatened to filibuster unless changes are made.

Sen. Edward M. Kennedy (D-Mass.), a leading proponent of the bill, attempted to force a vote Wednesday on requiring the Senate to move forward to consideration of the bill.

But Sen. Ted Stevens (R-Alaska), acting as majority leader until Sen. Howard H. Baker Jr. (R-Tenn.) returns from China, said yesterday he would wait until Baker gets back Monday to file a motion to end the preliminary debate so the Senate can take up the legislation.

Stevens said Baker will open "shuttle diplomacy" between the two sides to avoid a full-scale filibuster.

Key provisions of the Voting Rights Act are scheduled to expire Aug. 6.

The bill before the Senate is similar to one passed last October by the House, 389 to 24.

One of Helms' major objections is to a current provision in the law, also included in the new legislation, requiring nine states--including North Carolina--and parts of 13 others with histories of racial discrimination to obtain Justice Department approval before changing their election laws.

Helms would like the bill amended to make it easier for those jurisdictions to be removed from the Justice Department's supervision after a period of good behavior.