WASHINGTON (AP) — Mitt Romney's choice of Wisconsin Rep. Paul Ryan as his ticket mate magnifies the sharp philosophical policy divisions between Republicans and Democrats and assures that a lively debate over taxes, deficits and the role of government will command the home stretch of the presidential race.
But the selection also is a bold gamble for Romney, one that gave President Barack Obama and other Democrats a wider target at which to aim.
In naming Ryan, Romney wed himself far more closely to proposals that have made the 42-year-old House Budget Committee chairman a hero to tea party and other conservative activists and anathema to Democrats.
Enshrined in budgets twice passed by the Republican House but so far rejected by the Democratic-run Senate, Ryan's proposals would rein in federal domestic spending, lower tax rates and overhaul safety-net programs like Medicare and Medicaid for senior citizens, the disabled and the poor.
Previously, Romney praised the Ryan budget in general terms, calling it in line with his own ideas, "bold and exciting" and even "marvelous." But he hasn't given it heavy emphasis in his campaign speeches nor singled out specifics.
Romney's own economic prescriptions have lacked detail in many areas. But from now on, he'll be compelled to defend what is suddenly a "Romney-Ryan" plan full of belt-tightening, smaller government proposals.
Still, clearly mindful of the controversy around the plan, Romney's campaign was trying to tread carefully.
Asked how Ryan's budget plan fits into Romney's campaign, Romney spokesman Kevin Madden emphasized that Romney's plan is distinct from his running mate's.
"Governor Romney is at the top of the ticket. And Governor Romney's vision for the country is something that Congressman Ryan supports," Madden said.
Voters may not make such a distinction, and Democrats certainly are eager to lump Romney and Ryan together.
Romney introduced Ryan during a Saturday tour of battleground Virginia as "an intellectual leader of the Republican party" who "understands the fiscal challenges facing America: our exploding deficits and crushing debt, and the fiscal catastrophe that awaits us if we don't change course."
Both sides agree that Ryan is smart, friendly and issue-oriented, even a little wonkish. But Democrats quickly trashed the ticket.
"By picking Rep. Paul Ryan, Gov. Romney has doubled down on his commitment to gut Social Security and end Medicare as we know it," said Senate Democratic leader Harry Reid.
Senior campaign adviser David Axelrod called the ticket "the definition of a fast track back to the failed, top-down economic policies of the past."
Such attack lines are sure to be sounded increasingly by Democrats in speeches and commercials.
Ryan's proposed Medicare changes are perhaps the most incendiary of his plan.
While current retirees or those near retirement wouldn't be affected, those now under 55 would be given the choice of enrolling in private-run insurance plans partially subsidized by the federal government when they reach retirement age.
Ryan's plan would also turn Medicaid into a federal block grant program to the states. And it calls on the White House and Congress to pursue modifications to Social Security, but without offering specifics.
In the past, Ryan has advocated letting younger workers invest their Social Security taxes in the stock market — a plan similar to one pushed unsuccessfully by former President George W. Bush.
Obama has ripped Ryan's proposals as "thinly veiled social Darwinism." And fellow Republican Newt Gingrich called Ryan's ideas for overhauling Medicare "right-wing social engineering."
Proposed changes to Medicare or Social Security are a deep concern to seniors, even if they wouldn't be directly affected. Those over 65 constitute one of the nation's most active voting blocs — aggressively courted by both parties.
Ryan proposes two new individual tax rates of 10 percent and 25 percent, lowering the top rate from the present 35 percent. He also would winnow "the burdensome tangle of loopholes," but without spelling out which ones.
Independent studies have suggested the net effect of such a plan would be to raise the tax burden on middle-class Americans while easing it on the wealthy.
While opposition to tax increases has become standard Republican dogma, polls show that a majority of Americans believe, with Obama, that the wealthy do not pay their fair share and should be taxed more.
Recent polls also show that Romney has failed to overtake Obama despite the still-dismal economy and some polls show that in recent weeks Obama has gained markedly over his rival.
While a fresh face on the national scene to many, Ryan "is totally a creature of Washington D.C.," said Ross Baker, a political scientist at Rutgers University in New Jersey.
In the sense that Ryan knows the ins and outs of budgeting and Congress, "that's a good thing for Romney. But I don't think it is all that helpful with the very people I think Ryan was designed to appeal to and to make sure conservatives don't stay home on Election Day," Baker said.
But business economist Peter Morici at the University of Maryland said Ryan's legislative background "complements Mr. Romney's private sector expertise wonderfully. He has a clear and concise plan to fix the federal budget."
"We won't duck the tough issues — we will lead," Ryan promised.
EDITOR'S NOTE — Tom Raum covers politics and economics for The Associated Press.
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An AP News Analysis