Last year, liberal activists produced a campaign video equating Mr. Ryan's budget plans to pushing an old lady in a wheelchair off a cliff. And Mr. Obama pointedly blasted Mr. Ryan in a closed-door meeting with donors in Chicago, saying he's "the same guy that voted for two wars that were unpaid for, voted for the Bush tax cuts that were unpaid for, voted for the prescription drug bill that cost as much as my health care bill - but wasn't paid for. So it's not on the level. And we've got to keep on, you know, keep on shining a light on that."
But Mr. Ryan has shown he's not shy about firing back at the president, bringing both budget numbers and sharp rhetoric to the fight.
"Rather than building bridges, he's poisoning wells," the usually mild-mannered Mr. Ryan said. "Exploiting people's emotions of fear, envy and anxiety is not hope; it's not change. It's partisanship. We don't need partisanship. We don't need demagoguery. We need solutions. And we don't need to keep punting to other people to make tough decisions."
Mr. Ryan's first go-around with Mr. Obama came even before he became Budget Committee chairman. He was one of the Republicans invited to the White House for the 2010 summit on health care, and in six minutes sliced apart the math behind Democrats' plans, arguing they didn't meet the president's own goals of cost-cutting.
Republicans feel the Ryan pick gives them an edge.
"Obama thinks he is smart and in command of the facts. Ryan actually is," said Mike McKenna, a GOP strategist.
Here's that 6 minutes of gold where Ryan sliced and diced Obamacare while the president sat there and seethed.