THE MANAGERS of about 60 American theaters gathered at the Hotel Washington last week to check each other's pulses, lay plans for the coming year, gossip a little, and pay tribute to Arena Stage on its 30th birthday.

It was, to be specific, the semi-annual meeting of LORT -- the League, of Resident Theaters. But a few of the delegates were willing to make a bolder claim for themselves. "we are the national theater of this country,"said Donald Schoenbaum, managing director of Minneapolis' Guthrie Theatre and the current LORT president. "The main item on the agenda was the coming round of negotiations with Actor Equity, whose three-year LORT contract expires next July. But among half a dozen other hot topics, the hottest -- for the nation's theatre,as for the nation itself -- was the election of our first actor-president.

"There's no question but that the people at this meeting are uneasy," said "sara O'Connor, head of the MilwaukeRepertory Theater. The federal government covers about 7.5 percent of the average LORT theater's budget, and about 23 percent of the gap between box office revenues and expenses.

"It's a huge issue," said William Wingate of Los Angeles' Mark Taper Forum, recalling Reagan's muted enthusiasm for goverment funding of the arts during his years as governor of California.

Shoenbaum took an optimistic view, resting his optimism on the Republician platform and the fact that federal support for the arts has become "established tradition." Another delegate even dared to speculate (anonymously) that the top non-profit theaters could be better off under Reagan -- if his appointees undo Carter's "populist" tendency to accompany every major grant with assorted lesser grants to lesser organizations.

An early omen, according to Wingate,will be tghe naming of a replacement for Livingston Biddle as chairman of the National Endowment for the Arts. "Our concern is that [Reagan] appoint someone with real stature and knowledge of the field, and someone who will have access to the highest levels of the government."

Among the specific matters of the moment:

The Broadway allure. Some resident theaters have become more Broadway-conscious -- and defensive about it -- after the success of such shows as "A Chorus Line" and "Children of a Lesser God," which have funneled money back into the non-profit institutions where they they originated. At the same time, several LORT-originated shows have flopped on Broadway recently, including the Guthrie's "Teibele and Her Demon," the Folger's "Charlie and Algernon" and the Mark Taper's "Zoot Suit" and "Division Street." Wingate and "division Street" (Steve Tesich's classical farce about the mid-life crises of former '60s activists) had shown him that "our audience has, in a sense, become more sophisticated than a New York audience." At the Taper, he said, the idea of "comedy" encompasses Moliere and Congreve and Shakespeare, but "when you say 'comedy' in New York, you tend to mean Neil Simon. The Broadway theater is oftentourists, and they come with narrower expectations -- and I don't mean anything against Neil Simon." (As well he shouldn't: The Taper was the launching-pad for Simon's latest broadway success, "I Ought to Be in Pictures.")

One reason it has been difficult to transfer LORT productions to Broadway, said O'Connor, is the gap in ticket prices. The Broadway audience comes to the theater with a less flexible attitude simply because it has paid more.

Cable TV. One delegate caustically predicted that video and cable-TV would soon take Broadway's place as the pot at the end of the LORT rainbow. Other delegates disagreed, but voiced a general desire to establish labor and royalty terms that would make TV deals practical and advantageous.

Postal rates. The present non-profit rate is 3.1 cents, and there has been talk of raising it to the neighborhood of a nicket -- "which is a lot of money," said Edgar Rosenblum of New Haven's Long Wharf Theater, "when you're sending out 200, 300, or 400,000 pieces annually, as we are."

New plays. On the one hand, LORT theaters are continually being urged (by funding sources) to do more new plays. But that means "brand new," so once a play has had its world premiere, it becomes less attractive. On the other hand, theaters that wish to do new plays frequently run up against the Equity "showcase" code, a contractual clause that allows preliminary scripts to be tried out at minimal cost in New York, so long as the same (unpaid) actors are hired -- or compensated -- when the play is done again. LORT theaters, and particularly those with permanent acting companies, are put in the position of having to pay actors they can't (and perhaps don't want to) use. "We won't do any of those plays," said Arena Stage's Tom Fichandler flatly.

A coalition of playwrights led by Michael Weller, author of "Moonchildren" and "Loose Ends," has sued Equity over the showcase issue, and LORT -- although named, ironically, as a co-defendant -- is making little effort to hide its sympathies. As LORT'c counsel Morris Kaplan put it, "I think it's fair to say that we don't take exception to the playwrights pursuing their interests."

Corporate funding. Many of the major foundations, including Ford and Rockefeller, reduced their support for the arts during the '70s. LORT theaters have been trying to encourage corporations to take up the slack.

For all the problems, the LORT delegatges met in an atmosphere of calm, if not outright confidence. When the organization was formed 15 years ago, it had 14 members. Today the number is up to 60, with half a dozen non-union theaters waiting in the wings.

Almost every theater begins almost every season with only the dimmest notion of how it will make projected income equal projected expenses. But as Arena's Zelda Fichlandler reassured the throng, the formula for surviving 30 years is simple. You just do it "one year at a time."