WASHINGTON -- Rep. Paul D. Ryan, the 42-year-old Republican named Saturday as Mitt Romney's vice-presidential running mate, is idolized by young conservatives in the House, who see him as a role model and a polished spokesman for their vision of America.
Many Republicans come across as dour budget-cutters with contempt for Democrats.
Mr. Ryan shares the politics of his conservative colleagues, but comes across as an optimist who relishes the opportunity to debate policy with Democrats.
After being elected to Congress in 1998, he vaulted to the top ranks of his party because he knew the ropes, studied the issues and could explain conservative tax-cutting and budget-cutting policies in lucid terms.
It has never been enough for him to attack Democrats and their proposals. He has always been eager to propose and defend alternatives, even at significant political risk to himself and his party.
Mr. Ryan is fluent -- Democrats would say glib -- in discussing the complex details of health policy.
As chairman of the House Budget Committee, Ryan has proposed huge changes in entitlement programs like Medicare and Medicaid.
The changes would help the federal government predict and control its costs, but could shift some costs to beneficiaries and to states.
He would convert the federal share of Medicaid into a block grant, giving each state a lump sum of federal money to care for low-income people.
States would have much more discretion over how to use the money.
To rein in Medicare costs, Mr. Ryan proposes to increase the age of eligibility, cap the growth in costs and have the government give a fixed amount of money to each beneficiary for buying private insurance.
Democrats say it would destroy Medicare.
Mr. Ryan did not back off. He tweaked his proposal. He would preserve the traditional fee-for-service Medicare program as an option for beneficiaries, but would force it to compete directly with commercial insurance plans.
In 2010, Mr. Ryan issued a "Roadmap for America's Future" that would have allowed workers under 55 to invest more than one-third of their current Social Security taxes in personal retirement accounts.
The plan would have simplified the tax code, abolishing many tax breaks and sought to promote savings by eliminating taxes on interest, dividends and capital gains.
Mr. Ryan is a member of the House Ways and Means Committee, which has jurisdiction over taxes, trade and Medicare.
Some Democrats call Mr. Ryan a fiscal fraud. They say by cutting taxes for corporations and the rich, he would perpetuate the deficit.
President Barack Obama recently described Mr. Ryan's budget plan as "an attempt to impose a radical vision on our country" and "thinly veiled social Darwinism."
In 2010, Mr. Ryan, wrote a book with Reps. Eric Cantor of Virginia, now the House majority leader, and Kevin McCarthy of California, the party whip, setting forth their vision: "Young Guns: A New Generation of Conservative Leaders."
The editors of Human Events named Mr. Ryan as "Conservative of the Year" for 2011.
But on Medicare and fiscal policy, he has sometimes worked with Democrats like Sen. Ron Wyden of Oregon and Alice M. Rivlin, a former director of the Congressional Budget Office.
Paul Davis Ryan was born Jan. 29, 1970, the youngest of four children of Paul and Elizabeth Ryan.
"Janesville is where I was born and raised, and I never really left it," Paul Ryan said Saturday, referring to the town in southern Wisconsin where he lives, not far from his childhood home.
Mr. Ryan received a bachelor's degree in economics and political science from Miami University in Ohio in 1992 and went to work as an aide to Sen. Bob Kasten, a Republican who represented Wisconsin.
From 1993 to 1995, he worked at Empower America, a conservative group organized by former Rep. Jack F. Kemp of New York and others.
From 1995 to 1997, Mr. Ryan was legislative director for Sam Brownback, a Kansas Republican who was then a member of Congress and is now governor.
Mr. Ryan is a fitness buff and hunting enthusiast. Before being elected to Congress, he worked at Ryan Inc. Central, a construction company founded by his great-grandfather in 1884.