There were some in the Mitt Romney camp who spent the last two days downplaying a Public Policy Polling survey that showed their candidate trailing Rick Santorum by a wide margin among Republican voters nationwide. Because PPP is a Democratic-leaning firm, they argued the stunning 38-23 percentage point lead given Santorum in that poll was unreliable. But with the release of three other national polls in the last day, there can be no doubt Santorum has, at the very least, caught up to Romney.

A new CBS News/New York Times poll shows Santorum with a 30-27 point lead over Romney with Ron Paul in third with 12 percent and Newt Gingrich bringing up the rear with only 10 percent. A just-published Pew Research Center for the People and Press poll shows a nearly identical spread for the two leaders with Santorum leading Romney 30-28, though it differs over the second tier candidates as its results give Gingrich 17 percent and Paul 12 percent. The latest Gallup tracking poll provides somewhat better news for Romney. It shows him still ahead by a slender 32-30 margin with Gingrich at 16 percent and Paul at 8 percent. These three polls provide solid proof that Santorum and Romney are now in a statistical dead heat. But no matter how you spin these numbers, it’s all bad news for Romney. The polls show him losing support among the independents who made him more electable in a November match-up against Barack Obama and show him trailing Santorum among the Tea Partiers, social conservatives and the political conservatives who make up the base of the Republican Party.

Going forward, Romney has advantages over Santorum in terms of financial resources and campaign organization. But if Santorum emerges in the next round of primaries as the leading conservative candidate who has the passion of the GOP grass roots, it could spell disaster for Romney. That is especially true if Gingrich continues to fade. Should the former speaker fail to raise enough money to continue a viable candidacy and thus drop into single digits, that could set up a one-on-one match-up between Santorum and Romney. This would be an interesting test of whether Republicans prefer a “true conservative” like Santorum over a relative moderate like Romney, who seems more electable.

Unfortunately for Romney, Santorum’s surge has come just at the moment when he has lost ground in matchups against Obama. Romney’s strongest argument for the nomination has always been that he has a much better chance of winning over wavering Democrats and independents who voted for Obama in 2008 than any Republican who is more identified with the Christian right. But in the wake of the tough attacks on Romney’s business record and taxes by Gingrich in the last month, as well as his gaffe about not caring about the poor, Romney is slipping in the match-ups against Obama and now appears to be doing not much better than Santorum.

This creates a difficult dilemma for the former Massachusetts governor. On the one hand, he must do his best to win over conservatives if he is going to prevail in the upcoming primaries. On the other, he must also not lose any more ground among independents if he is to maintain his edge in electability. But as it’s not possible to achieve both ends simultaneously, he must choose to concentrate on convincing conservatives he is one of them. It is on that uphill battle his hopes for the presidency rest.