Further troubling for the presumptive favorite is that more Republicans think that rival Rick Santorum best represents their values, and that more GOP voters would "enthusiastically support" him than Romney. Even then, only a third of Republicans say they would be excited to vote for the former Pennsylvania senator, while just over a quarter would be enthusiastic about punching a ballot for the former Massachusetts governor.

Romney's core of support comes instead from the 47 percent of voters who say it's more important to nominate a candidate who can win in 2012, rather than one with whom they agree on policy. Romney is the choice of nearly half of voters when asked who is most electable.

Still, the CBS polling numbers paint a troubling picture for Republicans looking to take back the White House in 2012, who know doing so is predicated on strong turnout from the conservative base. Nevertheless, GOP leaders might be heartened by a strong Republican bench of would-be candidates — including Chris Christie, Sarah Palin, Mitch Daniels, Marco RubioMarco Antonio RubioRyan pledges 'entitlement reform' in 2018 Richard Gere welcomes lawmakers' words of support for Tibet Dem lawmaker gives McConnell's tax reform op-ed a failing grade MORE, Paul RyanPaul Davis RyanMcConnell names Senate GOP tax conferees House Republican: 'I worry about both sides' of the aisle on DACA Overnight Health Care: 3.6M signed up for ObamaCare in first month | Ryan pledges 'entitlement reform' next year | Dems push for more money to fight opioids MORE, Bob McDonnell and Haley Barbour — whom voters continue to pine for.