Who is Paul Ryan?

— -- Gov. Mitt Romney is expected to announce Saturday morning that he's chosen 42-year-old Paul Ryan to be his running mate. Since 2008, the well-spoken Republican Congressman from Janesville, Wisconsin has emerged as a leading figure on the right and a champion of reduced government spending.

Ryan has earned the admiration of conservatives for the tough, government-slashing budget proposals  he's put forward since becoming chairman of the House Budget Committee last year. But when he first arrived in Washington as a freshman lawmaker in 1999 at only 28 years old, budget shrinking wasn't exactly in style.

Ryan told the New Yorker that he was "miserable" during the George W. Bush years, when a Republican-majority Congress added $5 trillion to the debt in war spending,  bank bailout, tax cuts, and other costs. But Ryan also usually voted with the majority at that time, though he put forward unsuccessful proposals to privatize Social Security and made other budget-slashing suggestions. In 2008, he released his "Roadmap for America's Future," which described his sweeping vision for how to make America's main entitlement programs of Medicare, Social Security and Medicaid solvent. The plan made him a hero among conservative circles, and Ryan eventually remade it as his "Path to Prosperity" plan, which President Obama and Democrats have criticized for embracing tax cuts while cutting government programs that help the poor. (It wasn't just Democrats--While running for president, Newt Gingrich called Ryan's plan "right wing social engineering," which probably help killed Gingrich's bid.)

President Obama only raised Ryan's profile on the right by critiquing his budget, and just last year, Ryan was  reportedly mulling his own run for president.

Ryan, an Ayn Rand fan, ably articulates a conservative vision for economic growth; a mark that Romney occassionally misses as he dodges the subject of his own personal wealth. "I think [Obama] looks at the economy as a fixed pie, and that it's government's role and duty to redistribute the slices in the name of equity versus our belief, which is 'Let's just grow the pie' and have an opportunity in our society for upward mobility — a society defined by upward mobility, not equal outcomes," he told Esquire magazine last year. "Under our view, we want to make sure people can get the opportunity to make the most of their lives, but that necessarily means that under the kind of economic-freedom system that we have had, you will have different outcomes of people's lives. And that's fine."

Ryan grew up the fourth child in a Roman Catholic family in Janesville that has lived in the town for five generations. He worked in his family's construction business after gaining his degree in economics from Miami University in Ohio. His father died when he was only 16, which prompted soul-searching that led Ryan to discover the works of Ayn Rand, who is still a major influence on him. He and his wife, Janna Little, have three children.