DES MOINES, Iowa (AP) _ Vice President Al Gore today won the endorsement of the largest union representing Iowa state workers, a major force in the nation's leadoff precinct caucuses.

The endorsement had been hard-fought, with allies of former New Jersey Sen. Bill Bradley urging union leaders to put off a decision.

Gore was headed to Des Moines to collect the endorsement of Council 61 of the American Federation of State, County and Municipal Employees, which represents more than 20,000 state workers.

The union is perhaps the biggest single political force in Iowa Democratic politics and Gore aides were trumpeting the endorsement. Just over 100,000 activists are likely to attend those caucuses, so the union's backing can make a big difference.

While AFSCME's national leaders have backed Gore, they left the decision in Iowa up to union leaders in the state.

``We think the vice president has been good for working families,'' said Council 61 president Jan Corderman. Corderman said leaders polled members and found 69 percent were favorable toward Gore.

The endorsement is a boost for Gore on several fronts. President Clinton has had tense relations with labor leaders because of his trade policies, and Gore has faced tough questions from unions worried about foreign competition for jobs.

But the union's decision was one indication labor leaders aren't ready to abandon the administration.

The endorsement will give Gore a cadre of experienced political workers who understand how to run phone banks, door-knocking sweeps and car pools. Those mundane tasks are at the heart of scoring well in Iowa.

Iowa's precinct caucuses open the presidential nominating season and those events demand a high degree of organizational skill. Candidates must find a way to deliver backers to thousands of neighborhood meetings around the state, where people spend an evening talking politics and declaring their choice in front of neighbors.

That requires more organizational skill than a primary election, where a voter drops by a polling place for a few minutes.