WATERLOO, Iowa — So much for the new, intellectual debate promised after the wonkish Paul Ryan joined the White House race.

In a flurry of charge and counterpunch Tuesday, the battle for the US presidency erupted, reflecting the fast deepening antipathy between the incumbent Barack Obama and his Republican challenger Mitt Romney.

Ryan's debut as Republican vice presidential nominee on Saturday, pundits predicted, would inject serious substance into a gutter trawling campaign, given his penchant for number crunching on budgets.

But the lauded battle of ideas lasted barely three days before the rival camps plummeted into faux outrage mode, waging spats unrelated to the economy, the central campaign issue.

Romney's braintrust decided their man should openly confront Obama after Vice President Joe Biden said in Virginia, which helped trigger a civil war over slavery, that the Republican candidate's banking reform would put people back in "chains."

"Mr President, take your campaign of division and anger and hate back to Chicago," Romney said.

But Obama did not take the bait, sending out his spokesman out to implicitly question Romney's suitability for the pressures of the Oval Office.

"Governor Romney's comments tonight seemed unhinged," Ben LaBolt said.

Earlier, the campaign teams were back to their comment-twisting best, clashing over Biden's choice of metaphor and the fabled tale of Romney driving to Canada with a pet dog on the car roof.

"Because of the president's failed record he's been reduced to a desperate campaign based on division and demonization," said Romney spokeswoman Andrea Saul, reacting to Biden's comments.

Saul also bemoaned past transgressions, citing an attack ad by a pro-Obama group in which a worker for a steel firm run by Romney's Bain Capital said his wife died from cancer after he lost his job and health insurance.

She also noted that an Obama advisor once questioned whether Romney lied to the American people or committed a felony over his tax returns.

The scene shifted quickly to Chicago, as the Obama campaign launched a rebuttal, denying there was a racial spin to Biden's remarks.

Obama deputy campaign manager Stephanie Cutter said Biden had been playing off Republican demands for the "unshackling" of the private sector from regulations designed to prevent a repeat of the economic crash.

"We find the Romney campaign's outrage over the vice president's comments today hypocritical," Cutter said, complaining that Romney had previously questioned Obama's patriotism.

"Now, let's return to that 'substantive' debate Mitt Romney and Paul Ryan promised 72 hours ago, but quickly abandoned," she said.

But the sniping is unlikely to end soon, though both sides probably would like it to.

Any day that Obama's camp is waging inane political rows, it is not having to defend the slow economic recovery, and 8.3 percent US unemployment rate.

Romney's team may have also welcomed Tuesday's brouhaha as a respite from increasing scrutiny of Ryan's record and the rationale for choosing him.

By dragging the president into the mire, they may hope to strike a contrast between the prophet of post partisanship that Obama claimed to be in 2008 and the more conventional politician he has become.

A slanging match may also help dent Obama's personal likeability ratings, which are boosting his bid for a second term on November 6.

In an especially sarcastic swipe, Obama said Romney's position on wind power -- which has growing muscle in Iowa where he is on a bus tour -- could be summed up thus.

"Governor Romney even explained his energy policy this way... 'You can't drive a car with a windmill on it.'" Obama said.

"I don't know if he has actually tried that -- I know he has had other things on his car," Obama said.

Obama's joke revived the story of the time the former Massachusetts governor put his pet dog Seamus in a carrier, strapped it to his car roof and drove to Canada on a family trip.

Democrats have used the story to suggest there is something strange and out of the mainstream about the multi-millionaire former venture capitalist.

This time the jibe did not go unanswered.

"After sanctimoniously complaining about making a 'big election about small things' President Obama continues to embarrass himself and diminish his office with his un-presidential behavior," said Ryan Williams, a Romney spokesman.