But as it is with most members of Congress, he is little known outside his district. So who is he?
At the Iowa State Fair Monday, Ryan talked about how much his kids love carnival rides. He also talked about policy, something he loves to do in excruciating detail.
Ryan had the numbers on the tip of his tongue when CBS News asked him this spring why he opposes the president's plan to raise taxes on the wealthy.
"He's talking about job creators -- 80 percent of all American businesses file their taxes as individuals, and the president wants their top tax rate to be as high as 44.8 percent," Ryan said.
Fellow Republicans consider him the "idea man" of the house. He's authored dozens of conservative policies -- on everything from privatizing social security to cutting taxes on capital gains and dividends.
Unlike many members of Congress, he revels in details, in policies like cutting the national debt.
"We don't want to have a situation where we're kicking the can down the road, assuming we can go on as we are," he said at a town hall last year.
Aside from a single year in the family construction business, Ryan has spent his entire adult life as a creature of Washington. He was an aide on Capitol Hill, then worked at a conservative think-tank and at 28 he was elected to Congress -- where he's been ever since.
The self-described "deficit hawk" strayed from that path during the Bush years, voting for the Medicare prescription drug bill and bailouts for banks, General Motors and Chrysler.
But Ryan has never wavered from his stand on social issues, especially -- as a conservative Catholic -- on abortion and his opposition to embryonic stem cell research.
In 2010 he told an interviewer, ''I'm as pro-life as a person gets.''
Friends in Janesville, Wis., where Ryan grew up, say his passionate belief in economic self-reliance comes in part from the fact that his father died when he was just 16.
Ryan is married. He and his wife Janna have three children -- ages 10, 8 and 7. And at 42, Ryan is the fourth-youngest major party vice presidential candidate in American history.
On Monday, he led his first campaign event solo. He did pretty well considering there were four or five hecklers who were extremely loud, standing in front of him. Ryan responded, "Hey, out here in Iowa and Wisconsin we treat people with respect" and said that the hecklers "must be from someplace else." The crowd loved it.
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