Paul Ryan used his first solo campaign swing as Mitt Romney's running mate Monday to hammer President Obama as a jobs killer, forcefully echoing Romney's message, while Obama used a pair of nearby campaign stops to accuse Ryan of hurting drought-stricken farmers.

Ryan was dispatched to Iowa by team Romney to challenge the president as Obama kicked off a three-day bus tour across the Hawkeye State.

Ryan, a Wisconsin congressman, was occasionally interrupted by hecklers during a speech at the Iowa State Fair but stuck to a meat-and-potatoes message of jobs and the deficit.

"As you see the president come through on his bus tour, you might ask him the same question that I'm getting asked from people all around America, and that is, 'Where are the jobs Mr. President?'" Ryan said in Des Moines.

But Obama, speaking on the west side of the state in Council Bluffs, strayed from his relatively reserved comments on Ryan a day prior and tried to pin the blame on Ryan for Congress' failure to pass a drought-assistance bill. It was a stinging charge to sling in America's breadbasket at a time of historically severe drought.

"Unfortunately right now, too many members of Congress are blocking the farm bill from becoming law," Obama said. "I am told that Governor Romney's new running mate, Paul Ryan, might be around Iowa the next few days. He is one of the leaders in Congress standing in the way. ...

"We've got to put politics aside when it comes to doing the right thing for rural America and Iowa," Obama said -- before touting his administration's decision to buy as much as $170 million worth of pork, lamb, chicken and catfish to help farmers affected by the drought.

The president's comments, though, were panned as blatantly political -- and misleading -- by Republicans.

While the Senate has passed a five-year farm bill, the GOP-controlled House nevertheless passed a narrower $383 million drought-and-disaster relief bill earlier this month. The Senate, though, wanted the broader farm bill dealt with, and it adjourned without acting on the House bill.

House Speaker John Boehner's office and the Romney campaign didn't let the Obama comment slide without a tough response.

"The Democratic-controlled Senate left town for August without taking action on a drought aid bill that passed the House with bipartisan support, including the support of Chairman Ryan," Boehner spokesman Kevin Smith said. "The weak attempt by the White House to manufacture a controversy illustrates the president's desperation to change the subject to anything other than his failures on jobs and the economy."

Romney spokesman Ryan Williams said Ryan "supported disaster relief, and the truth is no one will work harder to defend farmers and ranchers than the Romney-Ryan ticket."

Beyond his drought comments, Obama returned to criticism he made over the weekend about the Romney-Ryan pairing. Speaking in Council Bluffs, he called Ryan the ideological leader of the Republican Party, and one with whom he "fundamentally" disagrees.

The president so far is leaving the toughest attacks to his advisers and surrogates. The Obama campaign also went up with a new Web video Monday morning timed for Romney's arrival in Florida, where seniors are a key voting bloc. The ad ended with the message that is already a Democratic talking point: "Romney-Ryan, ending Medicare as we know it."

In Des Moines, Ryan focused squarely on the state of the economy as he made the case for a change in leadership.

"One thing we've got to get straight is we're not growing this economy like we need to. We're not creating jobs like we can in America," Ryan said. "(Obama) is making matters worse, and he is spending our children into a diminished future. ... On Nov. 6, we're going to change that."