Workers at Precision Castparts’ Portland-area plants voted by a 4 to 3 margin against joining the Machinists union, The Oregonian reported late Friday.

According to preliminary results released by the union Friday night, employees voted 1,258 to 932 not to join the International Association of Machinists and Aerospace Workers, the newspaper reported.

Precision Castparts is Oregon’s second largest public company and a key supplier to Boeing. It has several Seattle-area units, but only the Portland facilities took part in the union election.

Frank Larkin, a spokesman at union headquarters in Maryland, told The Oregonian the Machinists would keep trying to organize Precision’s plants.

“With that level of support, it’s not unusual for an organizing campaign to sustain several elections before representation is achieved,” Larkin said. “We don’t give up easy.”

Jay Khetani, a Precision spokesman, said before the vote that company managers would have no comment. But a management-backed Web site confirmed the preliminary election results Friday night.