For as long as there has been an AFL-CIO, it has spoken in the idiom of a Bronx plumber.

With the huge labor federation under the firm command of that venerable plumber, George Meany, the construction trades have been the first among equals - at the very least - in shaping the policies, priorities and image of the AFL-CIO.

The roughly 3 million unionized carpenters, bricklayers, plumbers, plasterers, painters, electricians, laborers and other construction workers comprise less than one-fourth of the 14.2 million AFL-CIO membership.

But they have a hard-hat esprit, cohesion, tradition and, above all, George Meany to count on - "a combination that's hard to beat," according to an envious industrial union leader.

So it was no real surprise when the AFL-CIO led off its ambitious, much-ballyhooed campaign in Congress this year with a bill to expand picketing rights at construction sites: the building trades priority goal.

The decision to move first with the so-called common situs picketing bill was made in early January by a five-man subcommittee of the AFL-CIO Executive Council, appointed by Meany to map legislative strategy. Only one of the five, Martin J. Ward of the plumbers, was from a construction union, but construction carried the day.

Although some members initially favored lumping all of the AFL-CIO's proposed labor law changes together into one big package, they were assured by the construction unions that the picketing bill had the votes to sail through easily and quickly if separated out and allowed to go first.

After all, it was drafted and ready to go, and it passed through Congress with relative ease last year and would have been law now if only President Ford had not gone back on an agreement to sign the bill because of election year pressure from conservatives. Now there was a Democratic president and even more heavily Democratic Congress, which labor had spent about $16 million helping to elect.

"It sounded like such a natural," mourned AFL-CIO public relations director Al Zack after the House reared up and killed the bill by 217 to 205 on March 25. "In hindsight," he conceded, "it was a strategic mistake."

The most common assessment was that organized labor took the House for granted, concentrating its efforts on breaking a threatened Senate filibuster against the bill while yielding the presumably safe House to a massive lobbying campaign by the construction industry and National Right to Work Committee.

But, within a number of unions outside the building trades, there were some privately voiced warnings that the problems run deeper than bad nose-counts and lobbying errors, stemming instead from what one dissident union leader called the "plumber's mentality" at the top of the AFL-CIO.

"It's a changing political world but institutionally it (the AFL-CIO) hasn't adapted," said an official of a union affiliate that sets its own priorities and lobbies accordingly "There's a smugness, a complacency, that's self-defeating, said another official of an AFL-CIO union. "Sinetunes I think they even believe their own propaganda about how influential they are."

meany's defenders say the charges are unfair, contending that he too was misled by the vote miscalculation and that his loyalties and interests extend far beyond the construction trades. Meany himself, they note, attached highest priority to reform of labor organizing laws, not the picketing bill. Besides, they ask, where were the critics when there was still time to affect the strategy?

Zack sums it up as "Monday morning quarterbacking," and at least one of the critics concedes that the construction unions' clout stems in part from the inability of others to develop and defend their own alternatives.

The in-house critics contend that changes already under way in the labor movement assure that curtain-raising status never again will be given to a bill like situs picketing or, if such a move is attempted, a major out-in-the-open fight will be waged to prevent it.

They point to the emergence of more outspokenly "progressive" leadership in unions such as the machinists and communications workers which, together with the public communications workers which, together with the public employees and the auto workers - who are expected to reaffiliate with the AFL-CIO later this year - could become a powerful countervailing force to the more conservative construction trades.

Perhaps as important, although less apparent on the surface, are changes within the construction unions themselves, including the elevation of younger, better educated, more progressive leaders to the front ranks of some of the trades.

The construction trades remain the most conservative bloc within the AFL-CIO but strongly supported the Democratic ticket last year. However, in 1972, in contrast, 7 of the 17 construction affiliates backed Richard M. Nixon.

While the changes are unlikely to deter the construction trades from pushing their own legislation such as situs picketing (and in fact may embolden them to push for more), the cohesion of the construction unions on some other issues is expected to dwindle as coalitions develop in pushing for new directions, especially when Meany steps down.