By STEVEN GREENHOUSE
Andy Stern, the president of the Service Employees International Union, went into its convention under heavy fire from one of its largest locals, but he emerged stronger — overwhelmingly re-elected for another four years and with his power consolidated.
At the convention in San Juan, P. R., which ended on Wednesday, the nearly 2,000 delegates followed Mr. Stern's lead and voted to give the union's top officials more power to bargain with large, nationwide employers, somewhat reducing the role of individual locals in negotiations.
Mr. Stern has repeatedly argued that as employers grow larger and operate at a national and even international level, unions must do the same. To help deal with these ever-larger employers, he persuaded the delegates to create nationwide industry bargaining councils.
The move advances what Mr. Stern calls his "justice for all" strategy of sometimes sacrificing pay gains for current union members in exchange for persuading employers not to resist organizing drives at some nonunion operations.
His fiercest in-house critic, Sal Rosselli, president of a California local representing 140,000 health care workers, said of Mr. Stern: "He succeeded in getting his plans passed. He emerged with more authority."
But Mr. Rosselli said Mr. Stern's critics made progress by making sure the voices of rank-and-file workers would increasingly be heard.
Mr. Stern boasted that his union had passed the two-million-member mark, by recently adding 22,000 home-care attendants in Massachusetts and 20,000 child-care workers in Pennsylvania. But some academics and rival unions say that number is exaggerated because it includes 300,000 workers who pay the equivalent of dues but are not full members. Mr. Stern vowed that the service employees would unionize an additional 500,000 workers by its convention in 2012.
Nelson Lichtenstein, a professor of labor history at the University of California, Santa Barbara, said: "I am impressed with Andy Stern's ambition for his organization and for the labor movement. He has a program that we're going to organize another 500,000 workers. They're putting money into it. It's not just bluster."
Senator Barack Obama, the presumptive Democratic presidential nominee, spoke by satellite to the convention on Wednesday, with the delegates vowing to do their utmost to get him elected.
In an unusual move, Mr. Stern said, "I pledge we will, before the next convention," gain legislation "that guarantees affordable health care for every man, every woman and every child." He also pledged that Congress would pass legislation to make it easier to unionize millions of additional workers.
In a move likely to upset some Democrats, the delegates approved an "accountability plan" in which the union would spend $10 million to pressure or punish political candidates who made pro-worker, pro-union promises, but broke them after being elected.
The union's leaders cite a primary last February in which the service employees played an instrumental role in defeating Representative Albert Wynn, Democrat of Maryland, because the union thought he was favoring business over workers.
A plan was also approved at the convention that would create 200,000 rank-and-file leaders that service employees union officials describe as a powerful army to help unionize workers and to work in political campaigns across the nation.
The union said it planned to spend $80 million on federal and state elections in the current two-year political cycle.