Campaign: Ryan to 'focus on substance' at debate

(CNN) -- Vice presidential candidate Paul Ryan will "focus on substance" on Thursday evening, October 11th in his debate face-off against Vice President Joe Biden, a senior adviser to Mitt Romney's campaign told CNN.

In seeking to set expectations for the GOP candidate, the adviser said the high-profile debate stage is "certainly a new environment for him."

"Biden has so much more experience debating in the Senate, during his two presidential campaigns and then again during the 2008 (general election) campaign," the adviser said. "Ryan is looking to focus on substance, which voters seemed to like about the Denver debate, and continue to drive the message about there being a clear choice between the status quo of Obama-Biden and charting a new course with Romney-Ryan."

The Romney campaign could be suggesting Ryan will steer clear from memorable one-liners -- "zingers" -- as Romney did in the first debate.

Top Democrats on Thursday predicted the competition would be scrappy but collegial.

Romney and President Barack Obama met just over a week ago for their first of three debate sessions. Romney was widely credited with having a significantly more successful debate than Obama.

Thursday is the only debate between Ryan and Biden. Romney and Obama go head-to-head next on Tuesday in the second presidential debate.

-- CNN's Jessica Yellin and Gregory Wallace contributed to this report

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