For Republicans, this year's election wasn't complicated - it was supposed to be about President Obama's handling of the economy. But suddenly this summer it became about the stumbles of Mitt Romney.
Now, with the choice of Rep. Paul Ryan, a boyish and sure-footed policy wonk from Wisconsin, Romney heads a Republican ticket that returns the focus to the economy, with a detailed and controversial budget plan on the table.
Ryan is the GOP's favorite deficit warrior, and his selection had been urged by numerous worried conservatives.
The buzz of the morning is that a decidedly nasty presidential contest might end up being "about something" after all, pitting Democrats against Republicans on the bottomless-pocketbook issues of spending, taxes, jobs and entitlements.
But the choice of the 42-year-old, a seven-term congressman, may be more perilous than that. Paul Ryan's public vetting has only just begun.
There's no doubt that Romney, who has been struggling in polls recently, has deftly recast November, at least for now, as a pivot point for the future - choosing a budget-cutter who could not view government more differently from Obama and the Democrats.
Ryan's attempts over several years to remake the normally untouchable Medicare program - he'd allow those under 55 to leave Medicare and instead buy their own insurance with government assistance - passed the House but was assailed by Democrats and died in the Senate. The plan was even criticized by Newt Gingrich as "right-wing social engineering."
But Ryan's ideas to limit entitlements remain hugely popular with most conservatives. If nothing else, Romney's pick of the plain-talking and personable congressman could attract deficit-worried independents and Democrats as well as charged-up Republicans.
"The GOP base, particularly the tea parties, will now be even more enthusiastic because this gives them a much more solid reason to want Romney to win as opposed to just wanting Obama to lose," Jonah Goldberg wrote in the conservative National Review this morning. "It shows that for all of the talk of Romney's timidity and cautiousness he can make a bold decision when he needs to."
Even before the two appeared on stage together, Democrats appeared delighted by the choice, eager to go after a Romney running mate who, they say, had targeted popular social programs and promised to - as Obama characterized it - "end Medicare as we know it."
As a preview of what will be coming, the Obama campaign released a statement saying: "Ryan rubber-stamped the reckless Bush economic policies that exploded our deficit and crashed our economy. Now the Romney-Ryan ticket would take us back by repeating the same, catastrophic mistakes."
Beyond the economic divide, though, the choice of the relatively unknown Ryan is not without substantial political risk:
•Who's in charge here? Unlike most vice presidential hopefuls, Ryan brings a clear and well-articulated agenda to the ticket, policies that, as Romney hinted to NBC News on Thursday, are "a vision for the country that adds something to the political discourse."
And Ryan told CNN back in April that Romney needed to offer voters "the right kind of referendum, the choice of two futures."
But if Ryan is seen as the intellectual engine of the ticket, where does that leave Romney? He is already under fire from Democrats and some Republicans for changing positions on issues such as abortion and the health care plan he pioneered when he was governor of Massachusetts.
•Is energizing the base enough? Political history is full of vice presidential footnotes who "energized" the party faithful but ultimately brought little to the election itself.
Democrats were ecstatic when Geraldine Ferraro was named Walter Mondale's running mate in San Francisco in 1984. But mired by questions about her husband's real estate dealings, she mostly watched as Mondale was crushed by incumbent Ronald Reagan.
More recently, of course, Sarah Palin's pop-star popularity had a flip side for John McCain's chances in 2008. Palin's "hockey moms" weren't enough to stop Obama's message of change.
At the same time, Ryan's blue-collar Wisconsin background and personal popularity - he has won his last six races with no less than 63% of the vote - could give Romney a boost there and in other Midwest states such as Ohio, which is desperately needed if any Republican is to oust an incumbent Democratic president.
•What about foreign affairs? Ryan has been in Congress for 13 years, including his chairmanship of the House Budget Committee. His career almost exclusively has centered on economics and the budget, so much so that he has called himself a "policy entrepreneur."
Democrats will question his foreign policy experience, and the contrast with Vice President Biden on that score could be a flash point at the vice presidential debate in Danville, Ky., on Oct. 11.
Still, it is rare that a vice presidential candidate's foreign policy experience - Palin's interview blunders notwithstanding - have counted for much.
•Can he be president? Finally, and possibly most important, will Ryan be seen as capable of stepping in as a potential president?
He is young at 42, although if elected he'd be the same age as Theodore Roosevelt, and older than vice presidents Dan Quayle (41) and Richard Nixon (40). The youngest vice president ever was John C. Breckinridge (36 when sworn in with Democratic President James Buchanan in 1857).
Presidential elections are more than policy debates, and how Ryan defines himself before the voters could be as important as the details of spending cuts and appropriations. A product of Washington - Ryan worked as a congressional aide and think-tank staffer before being elected at age 28 - Romney's vice presidential choice now must take center stage on his own, at least for awhile.
By David Colton, USA TODAY