Primary polls: Romney moves into a South Carolina lead, while Huckabee threatens him in Iowa

Two new early-state poll from the Republican race this morning, and both confirm why Mitt Romney is probably the front-runner for the race, but also why his position at the top of the field is so fragile.

First up is the Washington Post-ABC poll of Iowa, the same that showed Obama up two days ago. No such surprises here, but Huckabee is rising higher than usual:

• Romney has 28% to Huckabee's 24%. Fred Thompson comes in third at 15%, ahead of Rudy Giuliani's 13%. John McCain and Ron Paul were tied at 6%.
• And in one more shocking numbers, considering this: 48% of Huckabee's backers said their support is definite, compared to only 29% of Romney supporters! Furthermore, Huckabee gets 44% among evangelical Protestants and 29% among previous caucus attendees -- a sign that the Republican base does not want any in its Big Four.

This was followed by Rasmussen's new poll from South Carolina, which also has Romney in a tie for first:

• Romney and Fred Thompson are tied at 21%. In the last Rasmussen SC poll in September, Thompson had 24% and Romney had 15%.
• Behind comes a cluster for second-place between Rudy's 13%, Huckabee's 12%, McCain's 9% and Ron Paul's 8%.

I believe this is the first poll done by someone else than than ARG that has Romney in the lead or tied for first in South Carolina -- and it is a major development. SC had long been Romney's weakness, as his fabricated conservatism was thought to be more repulsive to voters here than other places... but ROmney started airing ads, and he has risen significantly since then. So much so that it is hard to image him losing South Carolina if he wins both Iowa and New Hampshire (and perhaps Michigan). And with such a sweep, can Rudy Giuliani really expect to survive January?

At the same time, the Iowa poll shows just how fragile Romney's support is. After leading the field massively for months, he is now entering a real and dangerous fight with Mike Huckabee -- one he could very well lose. Romney has been deemed invincible in the state since the summer as his rivals basically conceded the caucuses to him, and his entire strategy is based on Iowa. He wins here, he carries the momentum to New Hampshire and wins there... and then the same in South Carolina. But if he loses Iowa, the media will treat him like they treated Dean... and he can kiss the cycle of momentum (and probably the Republican nomination) good bye. Romney has a lot riding on those small 4% that separate him from Huckabee in the Iowa poll.