There are some encouraging signs for Romney, however. Republicans were more likely to say they were "very" or "extremely" enthusiastic to vote. And in a sign that the convention might at the very least done its job softening the candidate to voters, Romney's favorables actually outpaced the president's for the first time this year. Some 53 percent of likely voters had a favorable opinion of the candidate, his highest number to day. By comparison, 51 percent of voters had a favorable opinion of Obama.

Republican vice presidential nominee Paul RyanPaul Davis RyanThree-way clash set to dominate Democratic debate Krystal Ball touts Sanders odds in Texas Republicans pour cold water on Trump's term limit idea MORE also leads Joe BidenJoe BidenSanders supporters cry foul over Working Families endorsement of Warren California poll: Biden, Sanders lead Democratic field; Harris takes fifth Poll: Biden holds five-point lead over Warren among New York Democrats MORE in terms of favorables, with 49 percent of likely voters dating they had a positive impression of him — versus just 46 percent for Biden. But while Biden holds that 46 percent favorability when all registered voters are asked for their opinion — not just those most likely to vote — Ryan slips to 42 percent favorability.

Romney continues to lead Obama on the economy, while the president gets the nod on foreign policy and Medicare. Romney is considered the more decisive leader, and voters believe he has a more optimistic vision for the country's future.

The president, meanwhile, is more likely to be see as in touch with the problems facing the middle class and women.