Rep. M. Caldwell Butler (R-Va.) was asked the other day where he stood on the issue of a constitutional amendment designed to pressure Congress into passing balanced budgets each year.

"I'm sort of curious about that myself," Butler replied with a soft chuckle.

Candid indecision may be easy for a congressman such as Butler not seeking reelection, but it is a state of mind more difficult for most House members to sustain. In an election year, the balanced-budget amendment has put many of them between the proverbial rock and a hard place and they are having trouble deciding which way to move.

Butler admits to moving both ways. "I'm one of the original patrons of the amendment but not a very firm one," he said. He has not put his name on the discharge petition that would propel the amendment from the House Judiciary Committee to the House floor for a vote; nor does he plan to.

The discharge petition has become the central battleground in the often acrimonious struggle over the proposed amendment. The amendment this week is before the Senate, which is expected to pass it, and the general assumption is that the House, too, will approve it if it gets loose on the floor.

The opponents' strategy has been to keep it bottled up in committee, and so the discharge petition--a list of names resting on the House Clerk's desk--is the key to the battle. If 218 members sign it, the Rules Committee would have to send the amendment to the floor. By last week's end, nearly 150 signatures were on the petition.

Far more than the required 218 majority had signed on initially as patrons, but not all of them are willing to go the extra distance to discharge a standing committee of legislation it dislikes. It is considered bad form if not actually dangerous for a member to do so.

"It's considered to be a bad reflection on the committee," Butler observed, "and, of course. commitee chairmen are not happy when it happens."

Rep. Jack Hightower (D-Tex.) is also one who has moved both ways. He signed the discharge petition, then changed his mind and struck his name off. His second thoughts came after a little talk with House Majority leader James C. Wright Jr. (D-Tex.) but were based, he said, on a realization that there would be slim chances of rewriting the amendment if it came to the House floor under a discharge proceeding.

"I decided that I had signed it a little too early," Hightower said. "I am very much for it, but I also want a chance to amend it, and I probably would not have the chance this way."

The outcome is too close to call, and on both sides, curiously, is a degree of pessimism. The amendment's chief House sponsor, Rep. Barber B. Conable Jr. (R-N.Y.), says that getting about 170 names on the petition will be easy but the rest will be difficult. "The hard part lies ahead," he added.

On the other hand, the leading opponent, Judiciary Committee Chairman Peter W. Rodino Jr. (D-N.J.), is equally concerned. In an interview, he rattled off several reasons for rejecting the amendment--leading economists oppose it, and it could produce "chaos" in congressional budget-making--but turned up the palms of his hands with an air of helplessness.

"Despite all these arguments, the public seems to believe that there is some magic in balancing the budget," he said. "A lot of members who have signed the petition tell me privately that it's just too popular to resist."

Both sides have semblances of organizations with missions to encourage or discourage signing of the petition. Wright and others in the Democratic leadership are buttonholing members in hopes of keeping their names off the petition; Rodino and others have also warned selected interest groups--senior citizens, organized labor and others--that it would be in their interests if the amendment lies where it is. Conable said a special whip organization had been established to help the amendment's advocates enlist petition signers. The pressure will increase substantially if, as most assume, the Senate approves the amendment in the next week or two.