Democratic presidential candidate Barack Obama went before a labor conference in Dubuque today and attacked rivals Hillary Clinton and John Edwards.  

“You’ve got to see if folks walk the walk before election time, or are they just talking the talk during election time,” Obama said.

Without citing her by name, Obama suggested Clinton’s trying to have it both ways when it comes to trade. “When a candidate rails against NAFTA today, you know then I think it’s fair then to ask her where she was with NAFTA 20 years ago, right?” Obama said. One member in the audience yelled out, “Hey, hey,” others laughed, and many of the union members applauded. “…You don’t just suddenly wake up and say, ‘Boy, NAFTA’s a terrible thing,’ after having been for it.”

Clinton had appeared before the same regional United Auto Workers convention a day earlier, suggesting a “time out” on trade deals. Obama called for amending NAFTA and cited his vote against allowing Mexican truckers to drive long-haul routes in the U.S.

Obama also railed against unnamed “candidates” who support Right-to-Work laws, a reference to rival John Edwards who said in 1998 that he did not think North Carolina’s Right-to-Work law should be changed. “I have to just say this and I want to be perfectly honest, you know, politicians often say they’re pro-labor at election time no matter what it is that they’ve said or done before,” Obama said.

Dan Leistikow, an Iowa-based spokesman for Edwards, says Edwards does more than just speak the “rhetoric of change” but has taken steps to take on the corporate interests that threaten working Americans. Edwards is set to speak before the UAW’s regional conference Wednesday.

Click on the audio link below to hear a small portion of Obama’s speech, referencing Clinton & NAFTA.

AUDIO: Obama strikes at Clinton (mp3 runs 25 sec)