Rep. Paul Ryan, the youthful GOP policy maven whose deficit-cutting ideas have stirred controversy in both parties, learned politics and policy under the sway of a long string of mentors.

While still in college, the Wisconsin Republican began his career as a lowly staffer for then-Sen. Bob Kasten, R-Wis., followed by a speechwriting job for GOP vice presidential candidate Jack Kemp of New York and the conservative think tank Empower America, founded by Kemp and pundit William Bennett. He served as legislative director to Sen. Sam Brownback of Kansas before returning home to run for an open House seat, which he won in 1998 at the age of 28.

Ryan, who just turned 40, is now the ranking Republican on the House Budget Committee and commands the same prominence on fiscal matters that many of his mentors once enjoyed. Yet the budget and health care ideas he has offered as a conservative response to Obama administration policies are so controversial that many in his own party are keeping their distance.

His ideas for entitlement reform, for example, include a gradual replacement of Medicare with a voucher program for private health care. And he would modify the Social Security system to allow some payroll deductions to be funneled into private accounts.

Politically risky proposals for phasing out the premier government health care program for the elderly and reviving failed Bush-era efforts to privatize Social Security to address soaring deficits are not on the agenda of many GOP leaders, who sense an opportunity to win back control of the House in November.

House Minority Leader John Boehner, R-Ohio, another of Ryan’s former mentors, says that while there’s "a lot of good work" in Ryan’s “Roadmap,” it’s not and won’t be the GOP conference’s plan.

Republican squeamishness about Ryan’s proposals may help to explain why President Obama gave Ryan so much attention when he appeared at a Republican retreat in Baltimore recently — calling attention to a plan that many Americans think is too radical.

Obama told Republicans at the retreat that while he disagrees with Ryan’s blueprint, "I think Paul has made a serious proposal. I’ve looked at it. I know what’s in it."

White House Budget Director Peter Orszag was blunter, telling reporters that Ryan’s plan shifts too much risk from the government to individuals. “The Medicare program in particular is dramatically changed from its current structure,” Orszag said during a White House briefing on Obama’s budget plan Feb. 1. Ryan and the president got into it again at the Blair House health care summit Thursday, as they exchanged interpretations of the “cost curve” in Medicare and other seemingly wonky numbers that hold the key to taming health care inflation. They disagreed, and Obama seemed to dismiss some of Ryan’s more unconventional ideas.

Yet Ryan, who also serves on the House Ways and Means Committee, is undeterred.

“I don’t think this is a "way out there’ plan," he said recently in an interview between votes in the House. “It provides a sturdy and sound safety net for our country that is sustainable. Social Security, Medicare and Medicaid are valuable and important programs for our country but they are all going bankrupt and they need to be saved before they bankrupt our country and shortchange our citizens.”

Ryan, the son of a lawyer who died when Ryan was only 16, has spent practically his entire career in politics and public policy.

He is more conservative than many of the voters in the 1st Congressional District in southern Wisconsin, which went for Obama over Republican John McCain in the 2008 presidential election. In the House, he has largely voted in the Republican mainstream, although he has occasionally broken with his party by taking more centrist stands on foreign policy and some social issues.

In 2007, he supported the Employee Non-Discrimination Act, banning workplace discrimination against gays and lesbians and said he has gay friends. “They didn’t roll out of bed one morning and choose to be gay. That’s who they are,” he said, acknowledging he “took a lot of grief” for the ENDA vote from members of his own party, so much so that he “stopped worrying about it.” He says his attitude towards gays is a “generational thing” — less important to him than to older people, perhaps, and he is willing to go along with whatever the generals propose regarding gays in the military.

Ryan is a dynamic speaker, and has strongly advocated the line-item veto and changes in the federal budget process to impose greater spending discipline. In 2005, President George W. Bush was so enamored of Ryan’s willingness to go out on a limb (he criticized Bush’s tax cuts as too anemic) that the president offered him a job as White House Budget Director. Ryan turned him down, but the presidential attention gave him a higher profile in the House. Ryan used that increased visibility to vault over a dozen senior Republicans to become the ranking GOP member on the House Budget Committee.

Ryan was helped immensely by his long-standing friendship with Boehner, who recalls Ryan putting up yard signs for him in 1990 when Ryan was a student at Miami University in Ohio. "He’s a bright, hardworking young man and I think the world of him,” Boehner said recently.

Wasting little time in asserting his views on the Budget Committee, Ryan offered an alternative to the House Democrats’ fiscal 2007 budget, calling for deep cuts in spending on government services and entitlement programs, in an effort to balance the budget by 2012. The majority Democrats rejected Ryan’s plan out of hand, as did 40 Republican members, who thought the proposal went too far.

Last year, when Republicans refused to commit to a comprehensive response to the Democrats’ health care reform proposals and budget, Ryan rolled up his sleeves and prepared a finely detailed, expansive plan that spelled out his ideas.

Ryan’s plan would incrementally raise the eligibility age for Medicare from 65 to 69. Starting in 2021, new recipients would get vouchers to buy private health insurance instead of being in the government plan. The eligibility age for Social Security also would go up and benefits for upper-income recipients would be linked to inflation, not the wages they earned. And in the most controversial part of the plan, workers would be allowed to put some of their payroll taxes into personal savings accounts, not the overall Social Security program.

Ryan defends these ideas as necessary to “save” the programs. Opponents charge he’s a wolf in sheep’s clothing trying to scrap the services altogether.

Whatever the motive, Ryan has gotten plenty of attention. He’s highly sought after as a speaker and has been invited to make appearances in first-primary-state New Hampshire this year. He stresses, however, that he doesn’t have the fire to run for president.

"My head’s not that big and my kids are too small,” he said, citing his children, who are five, six and eight years of age. Ryan returns home every weekend to the town of Janesville, Wis., where he grew up.

Ryan may be interested in running for the Senate someday, but hints he won’t challenge Sen. Russ Feingold, D-Wis., his friend and fellow Janesvillian with whom he has sponsored line-item veto legislation. The seat of Sen. Herb Kohl, D-Wis., could be a possibility in 2012, particularly if Kohl chooses not to run. Kohl emphatically refused to comment on anything about Ryan — his potential candidacy or anything else.

Former House Budget Committee Chairman John Kasich, R-Ohio, now a candidate for governor, is another former Ryan mentor. The hyperactive Kasich says he sees Ryan as a little like himself — not afraid to stick his neck out for ideas even if they are not universally accepted.

"I’m the expert on being rejected in the party on ideas that get blocked,” Kasich said in between campaign stops in Ohio. “He’s going to get his way over time. He’s getting more and more stature and more and more recognition. He thinks outside the box and he’s having a ball."