The Republicans' newly-chosen vice presidential candidate wasted no time in attacking Barack Obama's economic stewardship in his first solo campaign event.
In his first day campaigning alone as Mitt Romney's running mate, Paul Ryan quickly established himself as the chief attack dog in the fight to prevent Mr Obama from winning a second term.
The 42-year-old seven-term congressman from the Midwestern state of Wisconsin also showed himself to be a lightning rod of sorts, generating huge excitement among conservatives and equally strong disdain from Democrats opposed to his plans to reshape Medicare, the government's healthcare programme for pensioners.
Mr Ryan, facing thousands of cheering supporters in the crucial heartland state of Iowa, accused Mr Obama of "spending our children into a diminished future".
He faced off with Mr Obama as the president began a three-day tour in Iowa, which will be closely contested in the state-by-state race for the White House.
"As you see the president come through in 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?'" said Mr Ryan, clad in jeans, cowboy boots and a red-and-white check shirt.
Mr Ryan is the architect of a polarising plan approved by Republicans in the House of Representatives that would set up a voucher-like system to let future pensioners shop for private health cover or choose a government plan modelled on the traditional programme.
Independent budget analysts say that would probably mean higher out-of-pocket costs for OAPs and Democrats say it will be the end of Medicare.
While his reception was largely positive, protesters interrupted his brief fairground address several times, chanting: "Stop the war on the middle class". One woman climbed on stage with Mr Ryan before security could drag her away.
"She must not be from Iowa," Mr Ryan said as he tried to focus on his speech.
Later, as he raced through the fairgrounds with a mob of supporters and reporters in tow, one fairgoer shouted: "Do you really want to cut Medicare?" Mr Ryan did not respond - in fact, he did not directly address his controversial budget plans during his debut in Iowa, a swing state Mr Obama won in 2008.
Mr Ryan declined to address Mr Obama's claim that he was among House of Representatives Republicans "standing in the way" of legislation designed to help the drought-stricken heartland.
"If you happen to see Congressman Ryan, tell him how important this farm bill is to Iowa and our rural communities," Mr Obama told a crowd. "We've got to put politics aside when it comes to doing the right thing for rural America and for Iowa."
Mr Ryan said only that he would get into "those policy things" later.
But the Romney campaign issued a written statement on the issue. "The truth is no one will work harder to defend farmers and ranchers than the Romney-Ryan ticket," Romney spokesman Ryan Williams said. Ryan spokesman Michael Steel later blamed Senate Democratic leader Harry Reid for blocking a farm aid bill endorsed by House Republicans.
However, Mr Romney tried to separate himself from his running mate's budget plan, telling voters in Florida that the Republican ticket wanted to "make sure that we preserve and protect Medicare".
Three months from election day, polls find Mr Obama with a narrow lead over Mr Romney in a race defined by a weak economy and high unemployment.
Mr Ryan, a favourite of the small-government, low-tax tea party wing of the Republican Party, brings to the Romney campaign an austere message on government spending.
He also brings enthusiasm from the party's conservative base, which has only reluctantly backed Mr Romney because of the moderate positions he once took on social issues.
As Mr Romney campaigned in Florida, Mr Ryan worked to connect with Iowans on a personal level, suggesting he was in the presence of "kindred spirits".
"We are united as upper Midwesterners," the native of Wisconsin, a state famous for its dairy industry, declared.
Standing alongside Iowa governor Terry Branstad, Mr Ryan told one fairgoer that he knew how to milk cows.
"We do cow milking contests in Wisconsin," he said.