Joe Biden, a Democrat who does not "tolerate" or "have regard for" labor unions but actually believes in them, delivered the single most powerful speech by of the top Democrats who showed up for this week’s Labor Day rallies, parades and picnics.

The vice president did it not just with rhetoric but with a genuine call to action for workers in Ohio, where he happened to be speaking, and across the country,

What distinguished Biden’s speech from the others by prominent partisans was that there was nothing timid about it. This was a rip-roaring populist pronouncement.

Biden got it. He took a side. No apologies. No soft messaging.

This was a pro-labor message from a pro-labor vice president.

“The battles labor won over the years not only raised the standards of labor but for everyone,” declared Biden, as thousands of union members cheered. “The other side has declared war on labor’s house and it’s about time we stand up. Understand it for what it is…. They’re reopening fights we thought we settled fifty years ago.”

Condemning Republicans for launching what he described as an anti-worker "onslaught," the vice president shouted: “The middle class is under attack, but labor is under the most direct assault in a generation!"

Without organized labor, Biden said, the fight for working America is lost.

“You are the only non-governmental power that has the power and the capacity to stop this onslaught,” he told the union members. “Without you there, there is no restraint."

Biden came to the battleground, the middle of the country, where public employees and teachers have been battered by anti-labor bills passed by newly empowered Republican governors and legislators.

In Ohio, voters will decide in November whether to overturn one of the crudest and most destructive of those anti-labor laws. Governor John Kasich, one of the savviest of the Republican leaders, secured passage of a number of laws that were designed to undermine the collective bargaining rights of public employees and to reduce the ability of organized labor to speak up for public services and education—in the workplace and in the political process.

Making the connection between laws that threaten unions and that threaten voting rights (such as the move by Ohio legislators to end early voting), Biden told the crowd in Cincinnati: “Repeal the laws this governor has passed."

“Vote, vote your values!,” he shouted as the crowd roared its approval.

Biden’s stop in Ohio was a "Which Side Are You On?" moment.

If he had come to one of the Midwest battleground states and failed to acknowledge the on-the-ground fights for labor rights that are playing out this year, he would have confirmed fears that the Obama-Biden administration is planning to keep labor at arm’s length in 2011. But his speech—much firmer and more focused than President Obama’s auto-industry focused address to Detroit union members—left no doubt of his position.

Obama is unlikely to ever get as fiery as Biden. Vice presidents often serve as pointmen in the struggles with political rivals and in efforts to energize the base.

But there was no mistaking Biden’s message. And it is one that the president and the rest of the administration would be wise to embrace—not just as a part of Thursday’s jobs speech to Congress, where the president should speak up for embattled public employees, but as part of a broader message for what will be a contentious fall.

“We’ve been through a lot of fights, but this is a different kind of fight," explained Biden. “This is a fight for the heart and soul of the labor movement. This is a fight literally for our right to exist. Don’t misunderstand what this is…. You are the only folks keeping the barbarians from the gates.”

Biden chose on Labor Day to stand with those who are battling the barbarians at the gate.

Obama should join him there. It is the right thing to do economically and politically.