Senate Majority Leader Howard H. Baker Jr. (R-Tenn.) yesterday abandoned his plan for a simple 10-year extension of the 1965 Voting Rights Act only a day after he proposed it.

Baker told reporters that the idea of a simple extension drew objections from both sides in the voting rights dispute and observed, "It was probably one of the shortest-lived trial balloons in history."

Baker's turnabout probably means that the extension will not come up in the Senate until next year, when a bitter battle is expected and a filibuster is possible from conservatives who oppose relatively tough extension provisions approved this year by the House. However, some liberals, including Sen. Charles McC. Mathias (R-Md.), continue to push for consideration of the measure this year.

Not only Sen. Edward M. Kennedy (D-Mass.) and leading civil rights groups but Senate Judiciary Chairman Strom Thurmond (R-S.C.) raised objections to Baker's proposal, although neither side appeared to oppose the idea of using it as a starting point for debate this year.

Kennedy and civil rights groups wanted the law clarified to assure that the government doesn't have to prove discriminatory intent, as well as discriminatory effects, in voting rights cases. Thurmond reportedly wanted to make it easier for states and localities to get out from under enforcement provisions of the law.

Asked why Baker proposed action this year only to abandon the idea in less than 24 hours, an aide said that, in addition to hoping for quick action this year, Baker wanted to show civil rights groups he is committed to moving ahead with the legislation.