The presidential campaigns of Mitt Romney and President Obama dueled Wednesday over Medicare, potentially a key issue in swing states that both camps are targeting in the November elections.

As Obama continued a swing through Iowa on the third and final day of a bus tour, Romney’s Republican surrogates scheduled events in Dubuque and Davenport — where Obama is speaking Wednesday — to highlight what Romney said was Obama’s decision to cut “$716 billion from the Medicare trust fund to finance Obamacare.”

The Obama campaign, for its part, stepped up its denunciations of plans by Romney’s running mate, Rep. Paul Ryan (Wis.), to overhaul Medicare and pointed out that Ryan’s proposed budgets would leave in place the very cuts that he and Romney are now condemning.

At the same time, the rival camps continued an increasingly testy back-and-forth over the tone of the campaign, with Romney declaring in a CBS television interview Wednesday morning that Obama’s reelection drive “is all about division and attack and hatred” and that he is “running just to hang onto power.” An Obama campaign spokeswoman called the comments “unhinged,” the Associated Press reported.

Romney also vowed in the interview, “My commitment is, if I become president, I’m going to restore that $716 billion to the Medicare trust fund, so that current seniors can know that trust fund is not being raided.”

The Romney campaign, meanwhile, released a new Spanish-language television ad Wednesday called “No Podemos Mas” (We No Longer Can). It highlights unemployment among Hispanics of more than 10 percent and says 2 million more Hispanics are living in poverty since Obama took office. Drawing a contrast to Obama’s 2008 slogan, “Yes, we can,” the ad includes a voiceover in Spanish saying, “We’ve got to tell them we no longer can.”

The Romney campaign did not say where the ad would run or how much is being spent on it. The Latino vote, highly coveted this election season, has traditionally favored Democrats, and polls show Obama leading Romney by a wide margin among Latinos. But Latinos are also believed to constitute the fastest-growing group of independent voters.

In Iowa, Obama was being joined Wednesday by first lady Michelle Obama. The Obamas don’t campaign together that much, primarily because they are considered more valuable apart, when they can cover twice the terrain. The last time Michelle Obama joined her husband on the trail was in May, for a stadium rally in Columbus, Ohio, that the campaign billed as a formal kickoff of election season.

They will make two appearances in Iowa on Wednesday, wrapping up the president’s bus tour of the state with speeches in Dubuque and Davenport. Iowa is important to Obama, whose 2008 campaign took off after he won the state’s caucuses. But it is also more challenging this year, in part because Iowa’s minority population is smaller than in other states, where it insulates him from the erosion of popularity he has suffered among white, independent voters.

The president’s tour across Iowa has been crafted to reach precisely that voter set. With more than a dozen stops across the state, he has reached into just about every living room. He has slammed Romney and Ryan for positions that Obama describes as hurtful to the middle class: failure to pass a farm bill to help drought-plagued farmers; plans to cut Medicare; and opposition to government tax breaks for alternative energy such as wind, which employs thousands in Iowa.

According to a campaign official, Obama will continue Wednesday to emphasize his argument that Romney’s tax proposals would harm the middle class.

Vice President Biden scheduled a campaign appearance at Virginia Tech in Blacksburg, Va.

Romney, who concluded a bus tour Tuesday in Ohio, planned to attend fundraisers Wednesday in North Carolina and Alabama.

Ryan was scheduled to hold a rally Wednesday at his alma mater, Miami University in Oxford, Ohio. As he met privately Tuesday in a Las Vegas hotel with wealthy Republican donor Sheldon Adelson for what the Romney campaign called a “finance meeting,” union demonstrators outside chanted slogans such as “Ryan, go home!” and accused him of “hustling for the 1 percent.”

In Chillicothe, Ohio, on Tuesday night, Romney lashed out at Obama with some of the harshest rhetoric of his campaign, accusing president of leveling “wild and reckless accusations that disgrace the office of the presidency.”

The already divisive presidential contest took on an even uglier tone after the former Massachusetts governor seized on the latest campaign-trail skirmish — a comment at a Virginia rally by Biden that Romney’s plans to loosen Wall Street regulations would “put y’all back in chains” — to go after his opponents.

“This is what an angry and desperate presidency looks like. President Obama knows better, promised better, and America deserves better,” Romney told a roaring crowd of about 5,000 supporters in Chillicothe. “His campaign strategy is to smash America apart and then try to cobble together 51 percent of the pieces. If an American president wins that way, we all lose.”

Romney added, “Mr. President, take your campaign of division and anger and hate back to Chicago and let us get about rebuilding and reuniting America.”

Throughout the summer, Romney has taken umbrage at the tone of the Democratic advertising barrage, but this week he ratcheted up his criticism. He and his advisers wrote much of the speech Tuesday on his campaign bus riding between stops in Ohio.

“Governor Romney’s comments tonight seemed unhinged, and particularly strange coming at a time when he’s pouring tens of millions of dollars into negative ads that are demonstrably false,” Obama campaign spokesman Ben LaBolt said in a statement.

Another Obama campaign spokesman, Danny Kanner, criticized Ryan for attacks on Medicare cuts.

“First, he attacked the president for the very same Medicare savings that he includes in his own budget,” Kanner said in a statement. “In the same breath, he falsely claimed that the Romney-Ryan budget protects Medicare — in fact, their plan would end Medicare as we know it, leaving seniors with nothing but a voucher in place of the guaranteed benefits they rely on today.”

Romney and his advisers have been using increasingly hot language to charge that the president has abandoned his 2008 themes of hope and change. But they became particularly incensed by an ad from Priorities USA, a pro-Obama super PAC, that suggests Romney is to blame for the death of a woman whose husband lost his job and health insurance after Bain Capital, a firm Romney co-founded, took over the steel mill where he worked.

Romney’s selection of Ryan, an intellectual leader of the conservative movement, as his running mate was expected to crystallize the policy differences between the Democratic and Republican tickets and elevate the conversation to a substantive debate about the federal debt and entitlement programs.

But the high-minded campaign has not come to be. Four days in, Romney’s campaign accused Biden of alluding to slavery, Obama joked about the time Romney drove his station wagon with the family dog on the roof, and Romney called the president “intellectually exhausted.”

And the candidates have yet to enter the post-Labor Day sprint, when things normally get tough.

Since Ryan’s selection, Democrats have celebrated the chance to use his controversial budget plan to alter the Medicare program to hammer the newly minted Republican ticket.

The Romney campaign launched a preemptive strike on Tuesday to embrace Ryan’s idea and say that it is Obama who is “actually damaging Medicare for current seniors.”

In a new television ad and in remarks delivered across the critical battleground state of Ohio, Romney accused Obama of “taking your money to finance his risky and unproven takeover of the health-care system.” Romney said in Chillicothe: “He is putting Medicare at greater risk. He is putting health care at greater risk. He is putting your jobs at greater risk. We will not let Obamacare happen.”

Romney’s advisers foreshadowed more efforts in the days ahead to define the Medicare debate on their terms. The campaign is trying to show voters that it will not shrink from Obama, even on politically treacherous terrain — including Medicare.

“Stay tuned. There’s a lot more to be had here,” Ed Gillespie, a senior Romney adviser, said in an interview. “We feel like this is a great debate, that the president is in­cred­ibly vulnerable here. . . . We have a plan to save it for future generations, which they don’t have.”

However, the move carries significant risk, particularly in Florida and Ohio, critical swing states that have many seniors — although it may be the only way to cushion Romney from the potential political fallout of Ryan’s budget proposal.

“You have to reform it for the younger generation in order to make the commitment stick for the current generation,” Ryan said on Fox News Channel. “President Obama is actually damaging Medicare for current seniors. It’s irrefutable. And that’s why I think this is a debate we want to have, and that’s a debate we’re going to win.”

The Obama campaign accused Romney of hypocrisy, noting that the Republican supports Ryan’s budget, which includes Obama’s $716 billion in baseline Medicare cuts.

The Obama campaign issued a memo Tuesday about the dim view many Floridians hold of Romney’s and Ryan’s statements on Medicare. Citing numerous recent polls and newspaper articles in Florida, the memo made the case that Romney’s selection of Ryan as his running mate will be a “game changer” in Florida.

“They’re spending millions of dollars on a lie to try to distract from the Ryan budget because they know it’s absolutely devastating for them with voters of all ages,” said Stephanie Cutter, a top Obama aide. “Unfortunately, the fact that both Mitt Romney and Paul Ryan want to turn Medicare into a voucher and raise costs for seniors by up to $6,000 blunts everything else in this conversation.”

The Medicare push came on a day on when Obama and Romney also traded blows over energy policy: the president promoting new homegrown sources such as wind to replace imported oil, and his GOP challenger journeying to coal country to accuse Obama of destroying the coal industry.

Romney has long assailed Obama for imposing regulations that he says have stymied business for producers of more traditional energy sources while favoring elusive alternative energies.

Yet on day two of his three-day campaign across an Iowa landscape where wind turbines are nearly as common as cornfields, Obama pounded Romney and pushed Congress to extend tax credits for the wind-energy industry — an effort Republicans oppose.

In Iowa alone, the industry employs more than 7,000 people, according to the Obama campaign; nationwide, that figure is 75,000. Obama has said that 37,000 jobs nationally would be at risk if the wind-tax credit is not extended.

Romney, the president said, has called new energy sources “imaginary” and Ryan has called them a “fad.”

“During a speech a few months ago, Governor Romney even explained his energy policy this way: ‘You can’t drive a car with a windmill on it,’ ” Obama said. “I wonder if he actually tried that. That’s something I would have liked to see.”

Then, Obama added: “I don’t know if he’s actually tried that. I know he’s had other things on his car.” It was a rare reference by Obama to Romney having once placed his dog Seamus in a crate mounted to the roof of his station wagon during a family vacation.

Rucker reported from Ohio. Branigin reported from Washington. Rosalind S. Helderman in Washington and Felicia Sonmez in Colorado contributed to this report.