FORTUNE — Congressman Paul Ryan (R-Wis) will deliver a dramatic challenge to the Republican presidential candidates at the CPAC conference in Washington, DC this evening. Without question, Ryan now stands as the intellectual leader of the GOP on economic issues. As Chairman of the House Budget Committee, Ryan has demonstrated a wonkish mastery of budget math. But it is his penchant for fearlessly advancing detailed solutions for fixing Medicare and curbing spending that has made him a hero to free market thinkers as well as a favorite target for President Obama. He has also become a controversial figure among Republican lawmakers, many of whom fear that his proposals, for all their specificity, are political poison.  Fortune obtained excerpts of Ryan’s speech, entitled “America Deserves a Choice,” and also spoke with the Congressman by phone this morning. Ryan’s address amounts to a bold manifesto on how the Republican candidate should frame the coming debate with President Obama. He warns that it would be a serious mistake to base the campaign on an attack of Obama’s policies. “We know the election cannot just be a referendum on President Obama’s failed leadership,” the address states. He strongly rejects the argument that the Republicans should strive to “win by default” and “just oppose” Obama.  Instead, Ryan advocates running on a policy-heavy platform that spells out precisely what the Republican candidate would do to build domestic energy production, rein in the debt, and alter the landmark healthcare bills passed in 2010. “Everybody knows this is politically risky territory,” Ryan will say in the address. “Republicans have battle scars on entitlement reform.”  MORE: Exclusive: Paul Ryan’s new manifesto on healthcare  But Ryan clearly thinks the electorate is more sophisticated, and more realistic about accepting the pain of necessary reforms, than do many Republican leaders. “Boldness and clarity offer the greatest opportunity for creating a winning coalition,” the speech continues. The address contains two fascinating insights –– bound to be dismissed in some quarters as naïve –– about America’s voters. First, Ryan states, “The President’s partisans are underestimating the ability of Americans to do the basic math.” In other words, Ryan believes the deficits running at over $1 trillion a year should and will become a gigantic issue if the Republican candidate exploit it, not by merely condemning Obama, but showing precisely where the budget reductions will come.  Second, Ryan argues that rather than taking comfort from vagueness, voters prefer concrete ideas. “Americans are seeking political leaders whose solutions are reassuring precisely because they are bold,” he intones.  In an interview, Ryan countered what’s bound to be the main objection to his speech –– that detailing entitlement cuts is a gift to Obama, and that the best strategy is to attack, stay vague on details, then enact a daring agenda once the Republican winner takes office. Ryan isn’t worried that the candidates are avoiding the big issues in their stump speeches and debates, though they embrace many of his ideas in their position papers. “I’m not concerned that they’re still nit-picking one another, and going down cul-de-sacs,” he says. “What matters is once the choice is made, that the candidate set the framework for an affirming election, with contrasting policies.”  MORE: Congress’ super committee: pain, punishment and payoff  The candidate, says Ryan, needs to run on a bold, specific platform in order to win broad support and get it enacted into law, once he’s elected. “We need an election where the country approves and gives us permission for bold reforms,” he told me. “The theme should be, ‘Here’s what I’m proposing to save America.’” The winner, he says, should capture a mandate for change based on the issues he runs on, and not spring a hidden agenda, buried in policy paper footnotes, on the public once the voting is over. “Running on the issues will give us the moral authority to get them enacted,” he says.  As an example, Ryan cites President George W. Bush’s 2004 reelection campaign. President Bush ran as a hawk on national security and pounded John Kerry’s voting record. “Then he proposed Social Security reform without talking about it much in the campaign,” says Ryan. “And we all know the results.” Ryan levels the same criticism at Obama, whom he accuses of running on a feel-good platform of “hope and change” then pushing policies that, he says, shocked a public unprepared for such wrenching, extreme measures. (Obama did campaign on reforming healthcare and bolstering financial regulation.)  Ryan also contends that getting specific is good politics. “If we don’t spell out our solutions, Obama will misrepresent what we want to do. He will get away with telling people we’ll behave in a harsh way, when what we really want to do is get in front of a possible debt crisis before, not after, we need to make draconian adjustments.”  MORE: Forget deficit reduction: Here comes more stimulus  In the Ryan playbook, the run-on-the-issues approach is sound politics for a second reason. “By proposing our own solutions, we can smoke out Obama, and force him to spell out his own solutions to the debt and healthcare problems.” Ryan charges that Obama’s remedies are always the same: raising taxes, placing price controls on Medicare that ensure long waits to see doctors, get procedures done, and a shift to rationing in general, and a shift to “hollow out” national security, as he puts it. For Ryan, the more people hear about those solutions, the less popular they’ll be.  As usual, Ryan’s ideas are daring, controversial, and bound to be ignored by the supposedly practical pols as idealistic and impractical. So far, as Ryan acknowledges, the candidates fighting over tax returns, the supposed evils of private equity, and past lobbying history, are a long way from the Big Ideas agenda he’s advocating as the road to victory. It may be less harmful for candidates and strategists to listen to the congressman instead.
The right's ideas man will argue that Republicans vying to displace President Obama this fall need to start talking about concrete plans instead of slinging mud.