The 1984 presidential race was Topic A as the AFL-CIO executive council convened its summer meeting here today and listened to Sen. Gary Hart (D-Colo.), one of the presidential contenders for 1984.

Hart was one of three Democratic presidential hopefuls invited to appear before the 35 chieftains of organized labor. Sens. Alan Cranston (D-Calif.) and John Glenn (D-Ohio) will appear in the next two days.

Lane Kirkland, president of the labor federation, has launched an effort to unite its 15 million members and its formidable grass-roots political machinery behind a Democratic candidate as early as December, 1983, more than two months before the first primary.

Kirkland and other council members favor this unprecedented step as a means of restoring--and increasing--labor's political clout after the divisions and defections of the Carter years.

The council is expected to announce Thursday its political committee's recommendations as to the timing and procedures for making an endorsement.

The group probably will agree to Kirkland's plan to turn a December, 1983, AFL-CIO gathering into a kind of political mini-convention, where the general board of 101 member unions--plus state and local officers of the federation--would vote to endorse one of the Democratic candidates, federation officials said.

Before that, probably as early as next summer, the local unions would vote on their choice. The unions' votes at the convention would be weighted for the unions' membership numbers.

Kirkland is recommending that a two-thirds majority be necessary for a candidate to win the endorsement. The endorsement process depends on the approval of the 101 affiliate unions in the first place, Kirkland noted.

"Unless we get that mandate, the federation will have to stay out" of the campaign process and will not be able to endorse anyone, he said. In this case the individual unions would be free to go their own ways--"and they would likely go in several different directions and tend to work against each other," he added.

Sen. Edward M. Kennedy (D-Mass.) and former vice president Walter Mondale, the two Democratic front-runners and old friends of labor, were not invited this week because both have addressed the AFL-CIO leaders recently. Other contenders will be invited to future gatherings, Kirkland said.

He acknowledged that Hart had criticized the endorsement plan as unfair for choosing one candidate so early and cutting off others long friendly to labor interests.

"Unless it the choice happened to be a senator from a western state, of his configuration, in which case he'd think it was a great idea," Kirkland said.

Hart was "well received," according to several present today.

Meanwhile, Kirkland likened President Reagan's balanced-budget amendment to a temperance lecture from W.C. Fields and to "sermons on sin while molesting the choir girls . . . . If Jimmy Carter could do it balance the budget why can't Ronald Reagan? Any fool can balance the budget on paper."

The president's labor liaison, Robert Bonitati, like the press an outside observer at the Grand Hyatt gathering, said, "I think it's a mistake" for the labor federation to exclude one political party from consideration. "But we can't force any private organization to do anything," he said.