Romney, Ryan bound by substance, differ in style

"When they're together, the energy they create with voters is very apparent," said Kevin Madden, a Romney adviser. "They have a great rapport together that really helps as we travel from one event to the next and from one state to another."

Still, the campaign is well aware of the problems that cropped up when past running mates garnered too much attention or were trusted prematurely to play a prominent role in the campaign. Alaska Gov. Sarah Palin infused John McCain's campaign with energy in 2008, but proved to be more of a distraction than an asset.

Charlie Black, a senior adviser to McCain's campaign, said he doesn't expect Ryan's popularity to become a liability for the Republican ticket.

"It's not a problem if the person stays on message," said Black, now an informal Romney adviser. "And Paul Ryan is going to stay on message."

Even as Romney seeks to benefit from Ryan's spotlight, he is distancing himself from some of his running mate's most controversial policy proposals. Embracing those positions could boost Romney's standing with conservatives, but also turn off more moderate voters.

Romney has repeatedly said the ticket was running on his budget proposals, not the budget Ryan crafted that calls for slashing spending and overhauling Medicare, the popular federal program for seniors. On abortion, the campaign says a Romney administration would not oppose abortion in cases of rape and incest, while Ryan opposes it in those situations.

Democrats, however, are doing their best to make Ryan — and his controversial budget proposals — the center of attention. President Barack Obama points to Ryan as the Republican party's "ideological leader." His campaign, in a play for seniors and middle-class voters, is running ads casting Ryan's proposals for overhauling Medicare and drastically cutting other social programs as outside the mainstream.

Democrats also have rebranded Ryan's budget the "Romney-Ryan" plan. They're also using Ryan's views on abortion to link the GOP ticket to Todd Akin, the Republican Senate candidate in Missouri who said women's bodies can prevent pregnancies in cases of "legitimate rape."

Pace reported from Fort Collins, Colo.

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