DETROIT — Vice President Joe Biden had a simple Labor Day message for unionized workers: Stick with President Barack Obama because the other guys are worse.

Biden told about 3,500 supporters Monday that the Republican ticket of Mitt Romney and Paul Ryan would roll back collective bargaining rights, denigrate their work and undermine the slow economic recovery under way.

One of Obama's top ambassadors to the working-class, Biden also sought with his remarks to keep a group of reliably Democratic voters motivated before an Election Day that is shaping up to be close.

"Romney and Ryan don't think that much about you guys," he said at the outdoor rally. "They view you, the working women and men of America as the problem. We view you as the solution. Look folks, we know who built this country and we know who is going to rebuild it. It's you. Instead of vilifying you, we should be thanking you. We owe you."

The Republican candidates supported measures to roll back collective bargaining rights for public union workers in Wisconsin and Ohio. Romney also has been critical of the National Labor Relations Board, accusing it of overstepping its role and suggesting it has become a proxy for Obama's union allies.

Separately, a review of Romney's economic proposals by the nonpartisan Tax Policy Center found that wealthier workers would benefit at the expense of the middle class, including many unionized workers.

All that has given Democrats an opening to appeal to populist elements in the party and, perhaps, distract from stubbornly high unemployment nationwide and in North Carolina, where Democrats open their convention Tuesday.

In response, Romney spokeswoman Amanda Henneberg argued that the middle class has been "crushed" by high joblessness, fallen incomes and rising gas prices under Obama.

"Americans aren't better off than they were four years ago, and they deserve a president who recognizes that," she said.

Biden also faulted Romney for opposing the federal bailout of the U.S. auto industry, and criticized Ryan for saying Obama promised to save a GM plant in Ryan's Janesville, Wis., hometown. The plant closed before Obama took office.

Biden said Romney's economic message doesn't add up.

"Folks, you can't say you're going to create jobs in the United States of America when you were willing to let 1 million jobs go under by the liquidation of the automobile plants he suggested," the vice president said.

"Ladies and gentlemen, you, organized labor, are one of the reasons why this country is coming back. Folks, let me make something clear and say it to the press: America is better off today than they left us when they left."

That line was a direct response to the argument the GOP will press during this Democratic convention week, that things are worse off now than they were four years ago when a Republican president left the White House.

"If it weren't so hot – if it weren't so hot – I'd go into detail but let me sum it up this way: You want to know whether we're better off? I've got a little bumper sticker for you," Biden said before chanting three times: "Osama bin Laden is dead and General Motors is alive."

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