Opponents of a proposed constitutional amendment designed to produce a balanced budget say they now have the votes to kill it in the Senate Judiciary Committee, 9 to 8. Discussion at a committee meeting yesterday, where the vote was postponed for a week, tended to confirm that.

Supporters asked for a delay, while opponents called for a vote as scheduled. Sen. Howell Heflin (D-Ala.), who couldn't be present, had asked for a delay so he could argue for the amendment. Sen. Alan Simpson (R-Wyo.), also a sponsor, said some changes in language have been drafted and delay would allow time to study them. c

Acting chairman Birch Bayh (D-Ind.), an opponent of the proposal, said any member is entitled to request a one-week delay on a vote. He told reporters afterward that if the vote had been taken yesterday the proposal would have been rejected. Supporters apparently hope some drafting changes will pick up the one vote they need to send it to the Senate floor. Opponents hope the current flurry of activity to balance the budget by legislative action will kill the effort to achieve it by changing the Constitution.

The proposed constitutional amendment would forbid federal spending from exceeding revenues in any year unless three-fifths of the House and Senate, instead of a simple majority, vote to permit it. Opponents contend that writing this into the Constitution is too rigid an approach.