The AFL-CIO, which has not endorsed anyone in the Democratic primary, announced Wednesday that it is sending more than 6,000 of its people to more than 22 states during the next two weekends to talk to more than 200,000 union voters about McCain.

"Senator McCain's economic path would lead to disaster for America's working families," said John Sweeney, president of the AFL-CIO, the nation's largest labor organization.

Meanwhile, the nation's largest union, the Service Employees International Union, is increasing its focus on the likely Republican presidential nominee. The union's political action committee is already running commercials critical of McCain's health care plan.

The SEIU, which endorsed Obama, has called the Illinois senator "the presumptive nominee."

"We've had a long process and the outcome is now clear," said Anna Burger, the SEIU's secretary treasurer. "The Democratic Party should come together to focus on winning in November."

But Clinton's union supporters say they're solidly behind her.

If the New York senator can win in West Virginia, Kentucky, Oregon and Puerto Rico _ the next four of the six remaining primaries _ then she can make a case to the Democratic superdelegates that she's the best candidate, said Gerald McEntee, president of the American Federation of State, County and Municipal Employees.

"The end of the road is not winning the nomination," McEntee said. "The end of the road is getting the victory in November ... We just believe Obama has a higher mountain to climb than Clinton to beat McCain."

Some of Clinton's most powerful union supporters _ AFSCME, the American Federation of Teachers and the International Association of Machinists and Aerospace Workers _ have re-declared their allegiance to Clinton and said they would continue to work for her.

"The answer is that the fighting Machinists are still fighting," IAM spokesman Rick Sloan said. "Full speed ahead!"