At the same time, some who want lower military spending figures supported the freeze although spending for many domestic programs, already cut sharply in the last three years, would be frozen. Meanwhile, others who seek a smaller military budget said they could not go with the freeze on domestic programs.

After the vote was initially announced, Senator Mark O. Hatfield, Republican of Oregon, chairman of the Appropriations Committee and one of the backers of the President's plan, switched his vote from no to yes, supporting the freeze. The switch is reflected in the final 65 to 33 vote. The Senator was not immediately available to explain the change. Closer Vote Was Expected

Earlier today Senate Republican leaders expected the vote to be close enough that Mr. Reagan, using a list provided by the leadership, made several calls to senators to lobby against the freeze plan. White House officials said the calls were made from Air Force One as the President was returning to Washington from Alaska.

But the President's plan still faces several other challenges, including efforts to reduce the military budget below the level the President has requested. The challenges are expected to carry the debate into next week. The Senate adjourned for the night after today's vote on the freeze and was to resume debate Thursday.

The President's plan, reduces the deficit by $144 billion over three years. Domestic spending would be reduced $37.4 billion and taxes would be raised $47 billion. In the 1985 fiscal year, military spending would grow by about 8 percent, after adjustment for inflation, over this year's budget. But this increase, and military spending increases in 1986 and 1987, are counted as savings in the deficit-reduction arithmetic because they are $40.2 billion below the President's initial projections.