Front-runner Mitt Romney and other Republican candidates are hitting every corner of South Carolina Friday, trying to secure a critical victory in the Jan. 21 primary.

But many of the former Massachusetts governor's challengers -- Rick Santorum, Newt Gingrich, Texas Gov. Rick Perry and Jon Huntsman -- are having trouble getting on different state ballots.
    
Nevertheless, they're still turning up the attacks on Romney's record as governor and in the business world. 

"Everyone can run the kind of campaign they want. I've run my campaign talking about the issues," Santorum said.

"You've heard about Gov. Romney and his deplorable record in Massachusetts -- and not one we want to have on the national stage juxtaposed to President Obama," he added.
  
Texas Rep. Ron Paul is the only other candidate who appears to have avoided the ballot pitfalls.

"This is why you need a real-life, no-kidding-around campaign," said Rich Galen, a GOP strategist and former Gingrich aide who is neutral in the 2012 race, told the Associated Press.

"All these guys who have been crowing that they found a new way to run for president, it's like saying I'm inventing a new airplane, and it has only one wing," he said.
    
Meanwhile, Gingrich is looking to get a jump in Florida.  The former House speaker is opening his Florida headquarters in Orlando this afternoon and then returning to campaign in South Carolina.