Rep. Paul Ryan (R-Wis.) speaks at a news conference in Washington. (Alex Wong / Getty Images )
By naming Paul Ryan as his running mate, Mitt Romney would be gambling that he can buttress the Republican ticket's standing on the economy while suffering no harm from the Wisconsin congressman's controversial plan to curb spending on such popular programs as Medicare.
Ryan, the 42-year-old chairman of the House Budget Committee, is the Republican Party's most prominent voice on fiscal matters. He has championed the party's drive to reclaim its commitment to fiscal restraint after years of letting the federal deficit swell.
Romney's choice of Ryan for the vice-presidential spot on the ticket would portend a fierce debate in the campaign's final phase over the size and role of government.
PHOTOS: The search for Romney's running mate
Ryan's prescription of cutting taxes, spending and debt has made him popular among Republicans -- and a star attraction on the party's national fundraising circuit.
But his fiscal plan, which passed the Republican-controlled House in April, has also made Ryan a prime target for Democrats in campaigns all over the country. Ryan's plan would transform the Medicare program for the elderly into a voucher system, offering subsidies for the purchase of private insurance to those who turn 65 starting in 2022.
The plan, which Romney has endorsed, would also cut $700 billion from Medicaid healthcare for the poor while lowering tax rates for the wealthy as part of a tax system overhaul.
In April, President Obama branded Ryan's budget "thinly veiled social Darwinism." He called it "antithetical to our entire history as a land of opportunity and upward mobility for everyone who’s willing to work for it."
Former House Speaker Newt Gingrich compared an earlier version of Ryan's plan to "right-wing social engineering," a remark that irked fellow Republicans who have essentially adopted it as their 2012 campaign platform.
As Romney's running mate, Ryan would have the potential to encourage a strong turnout of conservatives. With rare exceptions, Ryan has sided in Congress with the party’s conservative wing on abortion, immigration and most other issues.
On the electoral map, however, Ryan appears to offer Romney little help. Wisconsin has been a major battleground in the last several presidential races, but it is not one of the states that Romney must win in order to unseat Obama. The last time a Republican carried Wisconsin was in 1984, when Ronald Reagan was reelected.
A Catholic raised in Janesville, Wis., Ryan, who likes to hunt and fish, is a former fitness trainer known on Capitol Hill for his vigorous exercise regimen. He and his wife, Janna, have three young children. Ryan holds a bachelor's degree in economics and political science from Miami University in Ohio.
Ryan's rise in politics has been swift. He worked for several former Republican members of Congress: Sen. Bob Kasten of Wisconsin, Rep. Jack Kemp of New York and Sen. Sam Brownback of Kansas.
In 1998, Ryan returned to his hometown in southern Wisconsin to run -- at 28 years old -- for the House seat that he has held ever since. Ryan has been savvy about maneuvering upward in the Republican hierarchy in Congress. His expertise on fiscal matters led former President George W. Bush to offer him the job of budget director, a post that Ryan turned down.
Ryan has also appeared frequently on national television, honing media skills that he would need in the campaign ahead.
Follow Politics Now on Twitter