The lines were drawn yesterday for a contentious battle between backers of President Carter and Sen. Edward M. Kennedy (D-Mass.) over a proposed Democratic convention rule allowing the replacement of any delegate who wavers from the candidate choice expressed at the time of his or her selection.

Robert G. Torricelli, a former Carter campaign official serving as executive director to the convention rules committee, told a press briefing that it was "the great nonissue of 1980," because there is no evidence that any of Carter's delegates would bolt if freed.

But former Michigan congressman James G. O'Hara, a Kennedy strategist on the issue, told a sidewalk news conference outside Democratic headquarters that the Kennedy forces would try to delete or change the rule before next month's balloting begins.

Torricelli and O'Hara sparred on the issue of who was trying to "change the rules," with the former congressman contending that the Carter forces are attempting to violate almost 150 years of Democratic Party tradition, and Torricelli arguing that the Kennedy forces are seeking to overturn the delegate-selection rules by which all the convention delegates were chosen.

Their polite sparring was a prelude to what may be a more strident debate at the first meeting of the convention rules committee here next Tuesday. The issue eventually may come to the convention floor on the first or second day of the Madison Square Garden convention.

The Kennedy forces hope that by blocking the rule, they may encourage delegates to reconsider their pledges of support, and thus open the only apparent door for Kennedy to overcome Carter's 700-vote lead.

Both sides were ready today with legal and historical briefs supporting their positions, but Torricelli sought to create the impression that a Carter victory on the rules issue is as assured as his eventual nomination.

He said Carter had an 84-to-64 advantage on the rules committee, whose chairman is Sen. Daniel K. Inouye of Hawaii.

"Should there be a vote," he said, "it will very definitely be on candidate lines. I'm not aware of any Carter delegates who have any intention of changing the rules by which they were elected."

O'Hara also said, "I know of no delegate that intends to defect," but added, "If the nomination is so locked up, why do they need this threat" of removing a "faithless delegate?"

In a bit of psychological warfare, convention director Bill Dixon issued a tentative convention schedule showing the Democrats may have to be in session from early morning until after midnight every day in order to deal with all the rules and platform challenges coming from the Kennedy camp. With two hours of debate on 23 minority planks (all but five backed by Kennedy), Dixon said he had to schedule for 57 1/2 hours of business in four days, instead of the originally planned 28 hours.

Kennedy spokesmen have made it clear, however, that they do not intend to press for debate and votes on all their amendments.