Carter, Kennedy both invitng a showdown?

Preparations for a full-scale showdown between President Carter and Sen. Edward Kennedy at the Democratic National Convention in August continue to mount , even while top strategists on both sides warn against more internal party warfare.

Beneath the surface of the Carter-Kennedy tension may lie a more fundamental struggle -- between the Southern-rural-conservative and Northern-liberal-industrial wings of the party -- with implications beyond 1980, some observers believe.

Senator Kennedy's political fortunes could prove no better in 1984 or 1988 than in 1980, this reasoning goes. But he may by joined then by other non-Southern political powers and more liberal national trends. The Carter faction's intentions beyond 1984 are not known.

In this broader context, a Kennedy loss after intense effort in the 1980 four-year presidential cycle may seem a plus in the longer dynamic of party control. This, more than any realistic hope of loosening Mr. Carter's nomination grip, amy be spurring the Kennedy forces on, these observers suggest. And it may explain Mr. Carter's stone-hard refusal to meet the senator in debate.

In any event, both Democrat continue to raise the ante for party peace. On the Kennedy side:

* Assignments have gone out to Kennedy lieutenants for "a full delegate effort" -- to poll and court Carter delegates from all over the country, including the President's Southern stronghold, to ready a convention test.

* Fund-raising efforts, which have netted a steady $250,000 a week through the campaign, will be stepped up, with a July 1 direct-mail appeal to the 36,000 campaign backers to finance the convention drive.

* The senator's speechmaking schedule -- keyed this week on the Democratic platform hearings -- will be kept full.

On President Carter's side, White House forces are attempting to curb the senator's power to maneuver at the convention. They sought, unsuccessfully, to keep Kennedy backer William J. Green, mayor of Philadelphia, from heading the Pennsylvania delegation in August. But they did succeed at keeping Mr. Kennedy from appearing at the US Conference of Mayors session June 10 in Seattle, where he was to speak one hour after the President.

The Kennedy camp is counting on the dramatic focus of the Democratic National Convention itself -- with galleries of Newsmen and the public watching on live TV -- to approximate the one-on-one debate he has failed to get with the President.

Mr. Kennedy and his campaign staff remain apparenlty unpersuaded that their convention effort is futile, even though the President seems to have on overwhelming delegate majority. Richard Stearns, chief Kennedy delegate strategist, says the senator will have 1,300 delegates June 28, when the last state party will confirm its delegate count. Mr. Carter will have 1,925 delegates, by this estimate, and at least 125 will be uncommitted.

"I don't really look at delegates as Carter delegates, or Kennedy, or uncommitted delegates," Mr. Stearns says. "They are only delegates to the convention. The rule binding delegates to candidates doesn't have to be rescinded -- it has never been adopted.

"Fundamentally, the delegates themselves have to decide whether they are to be deliberative at the convention or whether they will just ratify the primary results. If the delegates adopt a deliberative role, fine. If they don't . . . they don't."

Some of Mr. Kennedy's most influential advisers say they have told Carter envoys privately: "You're going to have to make big mistakes to get Kennedy into a convention fight. He just wants a debate. Just don't do anything dumb."

Derisive comments by Carter people about Senator Kennedy, carried in the news media in recent days, are viewed by Kennedyites as inflammatory.

"They [Carterites] have a hard time grasping what conciliatory is," Mr. Stearns says. "They don't really feel like they've won. They want to play bitter-end politics."

The risk to Senator Kennedy in carrying a squabble with President Carter too far is that his forces could be crushed by a convention floor vote on whether delegates should deliberate the nomination issue anew or simply ratify the January-to-June caucus and primary results.

Many ardent Kennedy supporters, such as the Americans for Democratic Action (ADA), have fought in the past to keep the nomination out of party-boss hands at the convention. They prefer the primary system for binding delegates to candidates. The ADA will likely debate the open convention issue anew at its convention in Washington this weekend.

Meanwhile, Mr. Stearns concedes what outside observers say, that two things must happen for the Carter juggernaut to be over-turned in August: The Carter delegates must become convinced that the President is not re-electable, and they must be persuaded that Mr. Kennedy is electable.

So far, Mr. Stearns says, evidence shows Senator Kennedy would run better than Mr. Carter against Ronald Reagan in only a few states -- chiefly California , New York, and Pennsylvania.

National pollster I. A. Lewis says: "I've never seen any poll that shows Kennedy woudl run better against Reagan than Carter does, and I've been looking for four years.

"He'd have to convince Carter's delegates Carter can't win and he can. And he'd have to show this convention stratagem will not destroy the party -- which is difficult to do."

Mr. Lewis says he thinks Mr. Kennedy's 1980 performance has shown that the senator is himself basically "unelectable" -- possibly for 1984 and 1988 as well as 1980. "The public doesn't trust what he says," Mr. Lewis says. "They think he has bad judgment. The proof is that against a poor candidate like Carter, he's beaten 2 to 1."