WASHINGTON -- The largest union vote to take place in over 70 years may have to be done all over again, after an administrative law judge with the National Labor Relations Board recommended the results between two quarreling unions be set aside.

The ruling, by Administrative Law Judge Lana Parke, is the latest twist in the ongoing battle between the Service Employees International-United Healthcare Workers West and its rival offshoot, the National Union of Healthcare Workers, for representation at Kaiser Permanente facilities throughout the state.

Last October, some 43,500 Kaiser employees voted on whether to change unions in California--SIEU-UHW prevailed with 61 percent of the vote, thus maintaining its influence in California health care and an estimated $40 million in annual dues collected.

But NUHW contested the results, arguing that SIEU and Kaiser colluded to maintain SEIU’s control in representing Kaiser employees. Kaiser denied 2,300 Southern California employees, who voted to switch to NUHW, pay raises from a previous contract. SEIU subsequently used Kaiser’s denial to warn Northern California Kaiser workers that if they chose to vote for NUHW, they too would lose pay raises and existing contracts, according to NUHW.

Another NLRB judge found Kaiser’s denial of pay raises in Southern California to be in violation of the National Labor Relations Act, and the ruling by Judge Parke said SEIU was guilty of misconduct by using Kaiser’s actions in Southern California in voting materials. Such behavior “invited, if not provoked, the obvious inference that Kaiser’s conduct would be repeated,” according to the 34-page ruling. SEIU’s campaign “tended to stoke unwarranted and coercive voter fears.”

A message left with SEIU’s Oakland headquarters seeking comment was not immediately returned.

In a statement, Kaiser spokesman John Nelson said the recent ruling confirmed that Kaiser in Northern California lived up to its responsibility by facilitating the fall 2010 election in a “fair and neutral fashion.”

“As we have said repeatedly throughout this long process, Kaiser Permanente is entirely neutral in this dispute between the National Union of Healthcare Workers and the SEIU-United Healthcare Workers,” Mr. Nelson added.

SIEU has until July 28 to appeal the decision. The NLRB will then decide if another election should be held.

Thousands of medical assistants, respiratory therapists, medical records clerks and housekeepers across the North Bay will take part in the vote.

In Santa Rosa, about 1,250 employees were included; in San Rafael, about 800; in Napa, about 120; in Fairfield, about 113; in Vacaville, about 550; and in Vallejo about 1,900.

The NUHW was formed by former SEIU labor chief Sal Rosselli after he was ousted from SIEU.