MIDLAND, Texas (AP) — Republicans Mitt Romney and Paul Ryan are seeking to call President Barack Obama to account on several fronts, going after his stands on health care, taxes and the debt as the GOP ticket looks to build momentum heading into the party’s convention.

Obama, meanwhile, readied for a second straight day of criticism on the GOP ticket’s proposals on education, an issue that resonates with middle-class voters.

Romney and Ryan, campaigning separately Wednesday, were to level their criticism of Obama in three key battleground states: Romney was campaigning in Iowa, while Ryan had stops planned in Virginia and North Carolina. The campaign was also hitting the airwaves with a new television advertisement linking Obama’s divisive health care overhaul to cuts in Medicare.

The ad, titled “Nothing’s Free,” asserts that Obama raided $716 billion from Medicare in order to pay for his health care law. It’s the first ad Romney’s campaign has run focusing on health care since the Supreme Court upheld Obama’s federal mandate in June. And it comes as the Republican ticket seeks to gain the upper hand on Medicare amid charges that Ryan’s austere budget proposals would drastically change the popular federal benefit for seniors.

Romney has promised to roll back the Medicare spending cuts approved under Obama, while Ryan kept the cuts in his budget proposals. The campaign did not say where the health care ad would run.

Romney was flying Wednesday morning from Texas, where he held campaign fundraisers Tuesday, to Iowa. During remarks in a key Midwestern state, he planned to focus on the increases in the nation’s debt during Obama’s term.

Ryan, less than two weeks into his new role as GOP running mate, was focusing Wednesday on tax overhaul. The GOP campaign says Obama’s calls for letting George W. Bush-era tax cuts on people earning more than $200,000 a year expire at the end of the year would hurt small businesses because many file as individuals.

Obama was campaigning Wednesday in Nevada, one of the states hit hardest by the nation’s economic slowdown. The president planned to meet with teachers at a Las Vegas high school and promote his administration’s plans to make higher education more affordable before speaking at a larger event at the school.

Campaigning in Ohio Tuesday, Obama accused Romney of being oblivious to the burdens of paying for college. The president’s campaign sees education as another avenue for linking Romney to Ryan’s budget, which calls for $115 billion in cuts to the Education Department.

In a new ad released Wednesday, the Obama campaign suggests Ryan’s education cuts would lead to larger class sizes. A couple featured in the ad bemoans the prospect of increased class size and says Romney “cannot relate” to their desire to have the best public education system for their children.

The ad is running in Virginia and Ohio.

• Julie Pace, Associated Press