Back in the state that catapulted his presidential bid, Obama sought to undermine Ryan and, by extension, both Republican presidential candidate Mitt Romney and the GOP-led House. The president was back on his campaign bus, trying to snag some of the excitement flowing Romney's way since he named Ryan as his running mate on Saturday.
Noting that he and Ryan were headed toward the Iowa State Fair, Obama told a rally crowd that Ryan, the House budget committee chairman, is among the GOP leaders who have held up a farm bill as the Midwest endures a devastating drought.
"If you happen to see Congressman Ryan, tell him how important this farm bill is to Iowa and our rural communities," Obama said. "We've got to put politics aside when it comes to doing the right thing for rural America and for Iowa."
Obama also put the power of his office on prominent display, announcing plans to buy up to $170 million worth of meat and poultry from distressed ranchers and farmers. Iowa's six electoral votes could be pivotal in what has been a tight election.
Obama carried Iowa in 2008, but polls show a close race in the battleground state less than three months from Election Day.
Ryan was campaigning alone for the first time since getting the vice presidential nod. Romney was in Florida for a bus tour.
Romney's campaign, seeking to ratchet up support in Iowa, played up Ryan's upbringing in Wisconsin, which has a significant agricultural industry. Spokesman Ryan Williams said "no one will work harder to defend farmers and ranchers than the Romney-Ryan ticket."
Obama has urged Congress to pass a farm bill to provide a long-term solution for farmers. Democrats and Republicans are at odds over the program's farm subsidies and food stamps, with Ryan among the GOP lawmakers backing cuts in food stamp programs that are opposed by the president's party.
Ryan's events in Iowa could help determine whether conservative excitement for the Wisconsin congressman - and his austere budget plans - will overshadow Romney's message and Republican attacks on Obama's economic performance.
Romney briefly defended his new running mate's budget proposals for Medicare, telling Florida voters that the Republican ticket wants to "make sure that we preserve and protect Medicare."
"He's come up with ideas that are very different than the president's," Romney said of Ryan. "The president's idea, for example, for Medicare, was to cut it by $700 billion. That's not the right answer."
At the same time, a pro-Romney super PAC is spending more than $10 million on a new television advertisement attacking Obama's handling of the economy as the nation's unemployment rate lingers above 8 percent.
"Another month. Even more Americans jobless," says the narrator in the ad from the group, Restore Our Future, which is led by people with close ties to Romney.
The spot will air for more than a week across 11 presidential battleground states, including Colorado, Florida, Iowa, Michigan, Nevada, New Hampshire, North Carolina, Ohio, Pennsylvania, Virginia and Wisconsin.
Democrats are banking on Ryan and his controversial budget proposals overshadowing Romney's message and Republican attacks on Obama's economic performance.
Since Romney formally named Ryan his running mate on Saturday, the Obama campaign has been attacking the Republican budget architect's plans to transform Medicare into a voucher system and re-shape the nation's tax system.
A top Obama political adviser, David Axelrod, said Monday that Romney's selection of Ryan is reminiscent of John McCain's choice of Sarah Palin four years ago. He told "CBS This Morning" he remembers the initial excitement surrounding Palin's selection, but says he doesn't believe the choice of Ryan "is going to be a plus for Mr. Romney."
Axelrod called Ryan "a genial fellow" who advocates harsh policy positions, particularly on Medicare.
Ryan figures to play prominently in Obama's message during his three-day bus tour across Iowa, which marks his longest visit to a single state during the 2012 campaign.
Obama's bus tour will begin in Council Bluffs, just across the Missouri River from Omaha, Neb., and head across the state before wrapping up in Davenport along the Mississippi River.
Ryan, a 42-year-old congressman, is best-known for his proposing to reshape Medicare, the long-standing entitlement, by setting up a voucher-like system to let future retirees shop for private health coverage or choose the traditional program - a plan that independent budget analysts say would probably mean higher out-of-pocket costs for seniors.
Looking to define the Republican ticket's views on Medicare, the Obama campaign released an online video Monday featuring seniors in Florida talking about how Ryan's proposed changes to the popular health care program could affect them.
"It doesn't make any sense to cut Medicare," says one woman. The video aims to portray the Romney-Ryan ticket as a threat to Medicare and Obama as its protector.
The commercial comes as Romney gently tries to distance himself from his running mate's budget plan, making clear that his ideas rule, not Ryan's.
"I have my budget plan," Romney said, "And that's the budget plan we're going to run on."
The Romney campaign, meanwhile, released a new ad accusing the Obama administration of "gutting welfare reform."
The new television advertisement released Monday accused the Obama White House of stripping the work requirement from the nation's welfare law. It's the same charge the Republican candidate levied in a separate ad last week.
Independent fact checkers have found the premise of the ad to be false.